Inverter Heater E4 Error

If you are reading this, then you are probably suffering from the very common E4 or E2 Error Code being displayed on your Corona (or Similar) Inverter Heater also displayed as “F” error codes on some heaters.  The E4 Error Code is probably the most popular of the error codes which affect Inverter Heaters and this error can either be displayed from the moment the heater attempts to turn on, or it can occur intermittently, and sometimes the heater will work fine before eventually cutting out, with “E4” showing in the lcd display.

The Inverter Heater E4 Error code (and also E0 and E2) indicates either contaminated fuel or poor combustion, and is generally caused by failure to maintain the heater and its filters adequately, however on other occasions the E4 error occurs due to poor quality low grade fuel or water contamination within the fuel.

E4 Errors are more likely to occur if domestic heating oil kerosene is used in the Inverter Heater, due to the fact that domestic kerosene is stored in bulk for entire seasons in dirty underground tanks, however it can also occur in pre-packaged premium paraffin products, if the container has been stored in a cold location, exposed to air or has been stored for long periods and the fuel quality has degraded.

If your inverter heater is displaying the E4 error or the E0 or E2 Error codes, then you should do the following:-

1) Remove the fuel filter from inside the inverter heater, this is located in the bottom of the base, inside where the fuel storage tank sits, generally on all models its a small plastic mesh filter which just pulls out. Clean the mesh of the filter with clean Kerosene or Paraffin and scrub with an old toothbrush until its clean. DO NOT use water or any detergent.

2) Remove and clean the air filter located at the rear of the heater

3) Make sure that the fuel inside the tank is fresh. Fuel which has been stored inside the tank for several months, should be disposed off correctly, and the tank filled with new fuel. Always drain any used fuel from the heater tank into an airtight container, if the heater is to be unused for long periods.

4) Make sure that the heater is on a firm, level surface and that there is a reasonable space all around the heater. Ensure that the heater is the correct size for the room and that there is good natural ventilation present.

5) Buy a “Mr Funnel” filter, this is a special, re-usable funnel based filter which is designed to not only filter dirt from out of the fuel but will also remove all traces of water contamination which may have found its way into the fuel during storage or as the fuel ages. To filter the fuel, you simply pour the it from the original container into the heater tank using the funnel.

Using a Mr Funnel is a MUST if you choose to use domestic heating oil kerosene instead of premium fuel in an inverter heater on a regular basis, however it also prevents E4 errors from Pre-Packaged type premium fuels, especially if the containers are stored for long periods or in a cold location prone to condensation.

Following these basic steps will usually solve all, but the most stubborn E4 errors. However if you still get the same error after following the above advice, then you will probably need to clean out, and service the burner and combustion chamber inside your inverter heater. Check out our Servicing a Inverter Heater page for our step by step guide to cleaning and servicing these heaters, which includes pictures, and also a video detailing the procedure.

This information was taken directly from the user manual of a Corona Inverter Heater, as below.

The following image has been submitted to us by email from a blog visitor. The image clearly shows a large amount of carbon / rust / crud build up in the bowl under the heater combustion burner.

The sender assures us that this heater has been run on nothing but the recommended premium fuel. With this in mind, we now recommend filtering the fuel through a “Mr Funnel”, regardless of whether you chose to use the recommended premium fuel or standard Kerosene. We also recommend that this area of the burner is checked and cleaned out, during any routine servicing procedure. (Credit to “Mister B” for emailing us the image)

If servicing your Inverter Heater does not solve the “E” or “F” based error codes, then its probably time to replace the flame rod, which is the component most likely to fail and can produce one or more of these errors. If a replacement component cannot be found, there is an Electronic workaround described in the video below, which may restore the functionality of your existing part.

47 Responses to Inverter Heater E4 Error

  1. Roger Banks says:

    I am afraid that a lot of the above is simply incorrect. As authorised UK service agents of Corona Inverter heaters we do know how these things work.
    An E0 or E4 error is most commonly caused because the unit has not been run with sufficient fresh air ventilation and the flame current sensor and burner gauze have deposits built up on them. Cleaning the flame current sensor and burner gauze with a steel wire brush will remedy this. If this does not cure it then the problem is pump related due to contamination. These pumps are very difficult to service and may not be repairable at all if the teflon coating on the steel piston inside the pump has become scratched. You will need to replace the entire pump assembly (available from ourselves). Stick to good quality fuel ( not kerosene) and make sure you have adequate fresh air ventilation entering the area where it is running – yes that does mean leaving a window open.
    Roger Banks

  2. Wayside Garage says:

    The comment above reminds me of the response given by car manufacturers when
    they find a customer running their car on biofuel, the cries of its not a recommended fuel, and your pump will be destroyed may indeed be a valid warning but it doesn’t change the fact that many people do it, and judging by the number of cars i’ve seen running on it, one of them a Taxi doing thousands of trouble free miles it would tend to suggest that the majority get away with it, without any expensive problems. Back on topic I have a couple of these heaters in reception, I’ve run them for probably thousands of hours with no mechanical issues, I use them on standard heating oil purely because its what my space heaters and spray booth drier runs on and buying in bulk brings the price down to about 55p a litre. Times are tough, and I can’t afford the rapidly approaching £1.80 per L price for premium paraffin to run these for 8 hours per day so i’ll take my chances on the rough stuff. Maybe i’m just being unfairly skeptical but perhaps the guy above is not only writing out of his responsibility to convey the manufacturers information but also down to the fact that its winter and he probably has a warehouse full of the expensive stuff to shift?.

  3. Huw Watkins says:

    In fairness to Roger – his post was in response to my request for help with my inverter heater which wont fire and he has been very helpful.

    I have bought both a replacement pump and flame rod to see if they are the cause of my issues.

    Parts prices in my opinion are quite reasonable, so I suspect he is not just saying this to shift more expensive stock.

    Either way. I will know soon if this will fix my heater.

  4. admin says:

    @ Roger. Unfortunately I can take neither credit nor criticism in relation to these error codes as the information was actually copied verbatim from the user manual of a Corona Inverter Heater. I can only convey the information which was provided by the Manufacturer in good faith, on the basis that such information would be accurate and correct. Since I am unable to attach images to comments, I have edited the article above to include two screenshots of my user manual, both of which clearly list the main cause of E0, E2 and E4 errors as being water in the fuel, blocked filters or general fuel contamination, the very aspects which my article focuses on.

    If we then turn our attention to the troubleshooting section of the same manual, and the section which gives the solution to E0, E2 and E4 problems as being “Change to clean fuel” and “Remove water and clean filter” both of which form the entire basis around which the content of this article was written and the solutions i’ve given, and whilst I appreciate that there may other underlying or more complex causes which may also produce these Errors, consumers can only share the level of information which is freely given to them, which in this case, were the contents of the user manual, which is shown in the images above.

    So, I make no apologies for simply relaying this advice and in doing so, also giving instructions on how to remove any water contamination from within fuel, and whilst I respect that you have greater in-depth knowledge of these heaters, I do think it not only poor internet etiquette but also a little strong and over critical to open your very first comment here by branding the majority of an article as ‘simply incorrect’ when it was largely influenced from troubleshooting information which is contained in a manual which was produced by the actual Heater Manufacturer.

    I do also point out in the article, that if following the more basic advice of filtering the fuel (in order to remove any dirt and water contamination) and cleaning the fuel filter doesn’t solve the E4 error then they should strip down and clean the combustion chamber by following the advice and step by step procedure given on the linked servicing guide (and its embedded comprehensive 90 minute video) – part of which deals with cleaning the burner gauze and flame rod. So I’m not sure how that aspect of my article, in particular, is any different to a large chunk of your own comment, which advised cleaning the same components!.

    The only thing I didn’t mention was in respect of the fuel pump, perhaps this is because both of my heaters have run perfectly fine on Kerosene for over three years and they haven’t required any replacement parts. They also are my ONLY source of heating, so they do get a lot of use, probably more than most. Perhaps i’ve just been lucky in this respect, but suffice to say that if the pump failed tomorrow, then I have more than saved enough to replace the pump or cover the £150 cost of a brand new heater by choosing to run on Kerosene rather than on the recommended fuel, (a saving of around £1 a litre). So whilst your points regarding this have been duly noted, its a gamble for me, which has already paid off.

    I would also highlight the fact that a heater owner has commented on another article that they have been experiencing these type of problems and strange rust build up with a heater run entirely on Premium Fuel, so there are obviously no guarantees that problems won’t occur down the line when buying premium fuel at the premium price.

  5. MisterB says:

    And I am that owner !!!
    we bought our first heater in France about four years ago and haven’t had any issues with it over there, we normally always buy the premium fuel ‘sans odour’ (without odour but last year bought the standard fuel and to be honest there was very little difference. I am not sure though whether the fuel is actually paraffin or heating fuel, but its what we were told to buy!

    We then bought another one from the UK (a lot more than £150 though!) and have ONLY ever used premium ready packaged fuel, now at just under £30 for 20 litres. I would be interested to know the comparative cost of heating fuel – can it be bought in 20l containers? As I seem to be the only one who has had this issue perhaps I should be using normal heating oil?

  6. admin says:

    Hi, These heaters seem to run fine on both standard paraffin and heating oil, at least i’ve been running both of mine on standard 28 second heating oil (also known as Kerosene) since the day they were bought. The Corona Heater is now over Three years old, and the £150 KRE300 which I bought from Brico Bravo is Two years old and they both still run flawlessly.

    The only thing I do is to filter every fill of the fuel routinely through the “Mr Funnel” and every now and again I add some additive to the Kerosene which is called FastExocet or Boilermax. I also drain out and service each heater at the end of every Winter season.

    However, as per the comment from the Distributor above, these heaters are made to run on nothing but Premium Paraffin, which is basically the odourless fuel which you purchased in France. This premium fuel is still part of the Kerosene family, it just goes through a more intense refining process meaning that its supposed to be a cleaner burning fuel, which produces less soot and less odour and so it is generally the manufacturer recommended fuel for indoor paraffin lamps and heaters such as these.

    In short, standard non premium paraffin and heating oil are NOT the manufacturer recommended fuels, and using these standard non premium fuels is supposed to be bad for your heater and its components. This is why I find your own situation interesting – because you are paying well over the odds in order to use the correct premium fuel as stipulated by the manufacturer, but in comparison to me, you appear to be actually worse off in relation to heater reliability than if you had just used standard Heating oil (which costs a fraction of the price) because I have had non of the problems that you have experienced.

    I’m not saying that problems won’t occur when running on heating oil, moving parts wear out and may eventually require replacing through wear and tear when used on any fuel and Electrical failures on sensors are not unknown, but equally are not fuel related. All I am saying is that using Premium Paraffin, doesn’t seem to lessen the potential of combustion or soot / gunk build up issues happening. Personally, i’m just going to keep using Heating Oil, and i’ll continue to take the risk(s), and put that saving towards any future problems or component part replacements *IF* they should occur.

    To answer your question, yes Heating Oil is much cheaper than Premium Paraffin fuel. Using your own price example, you pay roughly £1.50 a litre for Premium Fuel, in comparison I pay 70p per litre from the pump at the yard of a Fuel broker, so that is less than half price. I just take a few 20L / 25L Jerry cans along to my local heating oil supplier and fill them from their pump.

    If you know anybody who has oil fired central heating, the costs for Heating Oil can be reduced even further, for example the current bulk delivery price for 500L – 1000L is around 53p per litre at the moment, that’s almost £1 per litre cheaper than the Premium Paraffin. Of course you need to know somebody who has heating oil delivered and who are happy for you to syphon a container or two from their storage tank!. But whether you collect the fuel in your own containers from a Broker, or buy from somebody who uses oil fired central heating, the savings are there – of course you run these heaters on non approved fuel at your own risk, but having heard the problems that you have still had when using the proper approved fuel, I don’t think that you have a lot to lose!!.

    In all honestly, using premium fuel in your heater is probably making it untenable cost wise. At £1.50 per litre of the Premium fuel, it works out that it is costing you about 15p per KW/h to produce heat – you may as well just get a cheap Electric Convector or Oil Filled Radiator. On a good Electricity tariff, it would only cost you 11p – 12p per Kw/h

    I continue to use my Inverter Heaters because at 70p per Litre for heating oil, it works out at 7p per KW/h and so it is cheaper than using Electricity to heat, around £35 – £40 a month cheaper to be exact.

    Interestingly, when first researching these heaters I found a few people in France who were professing to run these heaters on a solvent called “Shellsol D60” which could be bought locally for about Euro 0.60 per litre. Whilst I don’t recommend that anybody actually tries this (It isnt available in the UK anyway), it does show the wide and varied fuels which people seem to use in these heaters – probably because the recommended stuff is so expensive.

  7. MisterB says:

    hi, if it helps for the tutorial/information, I took a photo of the build up of crud in the chamber, I just need somewhere to send it to!

  8. admin says:

    You can send any information / photos for inclusion to admin (at) – replacing the (at) for the traditional email ‘@’ symbol

  9. Alexi Козинцев says:

    Thank you for your writings I follow your instructions and since I filter fuel my E4 error fault code has all gone away. Greetings from Ukraine.

  10. Asif says:


    I am also using kerosene inverter heater.
    It is giving an error of “HH” at LCD display after that it remains at LCD screen even you switch it off and then switch it on, it remains on LCD. please guide me to over with this error.


  11. admin says:

    Asif, what is the make and model number of your heater?

  12. AyMAN says:

    Dr sir
    Ihave error hh idont have any id about model after i conect elctric i have this error

  13. AyMAN says:

    The model no is fh-G 3211y

  14. admin says:


    This model of heater appears to never have been sold outside of the domestic Japanese market. As I am in the UK, I cannot find any manuals for this heater in English, nor am I familar with the model number because it has never been sold over here.

    All that I can suggest, is that you contact the manufacturer, Corona directly and either ask them for a manual for this heater, or what the ‘HH’ error code means.

    Here is the link to the Corona Contact Form.

  15. David C says:

    After reading all the tooing and frowing i guess that the information here is as accurate as possible for people in the uk who have either lost their manual or bought a second hand one that didn’t have a manual with it.
    Either way it is a great help for any of these heaters which develop problems with them, like mine which is not running. Pump runs when directly connected to a 12v supply but wont when connected up to the unit. The only thing that people say is to replace the pump which i dont think is always right when it just might be the following micro switch, 7824A JRC MK003G
    Its the switch that is connected to the pump via 3 prongs which push into the connection and is held in place by a small phillips screw.
    I am trying to find out how to test it and/or replace. Will update when i have success or solve one issue to create another :)

  16. admin says:

    If the pump is running fine when connected to a supply outside of and completely independent to the heater then its not likely to be the pump. The supply to the pump is controlled electronically switched either by a transistor driver circuit or an Electronic Relay (depending on heater manufacturer and model), so it could be a faulty component in its control circuit, or it could be a fault elsewhere in the heater which prevents the pump from activating.

    Its worth mentioning at this point that the heater will not start the pump until a set ‘test’ criteria is met, so if the system senses that there is a problem elsewhere, such as with the burner, CO2 sensor or flame rod, often the heater start up process will not progress to the point where the pump is activated – shutting down at that stage, therefore the possibility of any other underlying cause needs to be checked and ruled out before the pump, (or its control circuitry) is condemned.

    Does the heater display an error code?, does the combustion chamber preheat correctly? – usually the chamber is pre-heated for between 30 and 90 seconds before the heater starts the pump and runs the ignition process.

    I’ve no idea what the exact component is that you refer to as “7824A JRC MK003G” – photo’s will often help at this point, and you can upload photos quickly and without any registration process to – and then add the link to the image in a post on this blog.

    From experience, the only component that I am aware of which contains 7824 is a L7824 series 24v 1.5A TO220 voltage regulator, as can be found on the link below – it does also match your written description.

    JRC stands for “Japan Radio Company”, who are simply an Electronic component manufacturer based in Japan, so the JRC is not part of the component part number, but just the initials of the manufacturer who originally made the component, however any generic L7824 will work as a replacement, such as the one i’ve given from RS components.

    Voltage regulators rarely fail, but if you have access to a digital multimeter you can check the correct operation of the regulator before buying a replacement.

  17. David C says:

    Thanks for the response.
    I can confirm that i have seen 3 error codes so far, E4 was 1st, then E2 and E1.
    The crucible does get hot as in its current stipped state i can feel the heat and see the smoke coming off it.
    I have spoken to another friend who has more electrical experience than myself, that we will go on Skype this afternoon so he can watch the unit go through its cycle and then he will help me narrow, hopefully whats wrong and i will then update a response for you and hopefully it will help others. My friend runs 4 Corona 5006’s in his home as is far cheaper than central heating. He has always run his heaters on central heating oil and has had some problems over the years but as you have previously advised, its usually service related and 1 replacement fuel pump.
    I have found that it is a voltage regulator, 24v. I only tested the pump on 12v which is weird……

  18. admin says:


    Have you replaced the flame rod (AKA Flame sensor) ?. I suspect that this is the cause of your problem, the flame rod is the small metal rod with the curve in it, which sits in the flame path. When this is heated by the flame, it changes its resistance and feeds back the change to the control circuit board, which essentially tells it that the flame has successfully lit.

    Sometimes, if the rod has failed completely and its gone completely open circuit, or the resistance is drastically different to any value that the control circuit board expects to see, then the start up sequence is abandoned and the heater never ignites – often this would happen at the point where the pump is started to prevent fuel being pumped into the chamber (because the sequence gets abandoned at this point it often results in the pump being wrongly suspected as faulty).

    So I suspect that the pump simply isn’t starting up, because the circuit board isn’t switching it on, due to a failure being sensed elsewhere, – i.e the faulty flame sensor, and at least two of those error codes you have given are indicative of a flame sensor problem, so this would be the first thing that I would be replacing in your situation.

    24v components will sometimes work down to 12v, occasionally some components can have dual 12v – 24v capability.

    Like your friend, I also use these heaters as my main source of heat, in fact for the last 4 Winters I haven’t even turned the Storage Heating on (I live in a rural area with no mains gas), not only does it save me around £60 a month in Electricity during the coldest months, but it also gives me more control over the heat – I.E I can set them at whatever temperature I chose, and switch them on when I need them, unlike the Storage Heating which keep the house hot whilst its empty during the day, but are freezing cold by 6pm when I return from work. I also run them on domestic heating oil, and *touch wood* have had no mechanical problems or failures throughout. I do however routinely filter the fuel for water and dirt, and I also strip down and clean out the heaters every spring before they get packed away, ready for the next Autumn.

  19. David C says:

    Hi all,
    I have been in touch with Dry it out and after talking the issues through with Roger, i have decided to order a replacement pump.
    It will be delivered before the weekend so when i get it back together i will let you know if its sorted.
    On another note i bought a tayosan kerosene heater and have been running that for the last 2 years without issue however in the last few weeks, whenever i have it set on minimum and the room temp is the same as the set temp, after 2 minutes the units beeps a warning and shows a flashing fan signal. After another 30 seconds the unit shuts off. when its running at full blast its fine, it only has the problem when it is running on the minimum.
    Any thoughts please?

  20. admin says:

    I suspect that the Fan speed is controlled electronically on a two stage (low – high) basis, Manufacturers often do this in two possible ways, either by adding a resistance in the circuit in order to reduce the voltage, and so produce a low speed (in a similar way to the heater / demister fan in a car), or more likely in this application by some kind of motor speed controller I.C.

    I don’t have a schematic available, and my own heater is currently heating the room i’m typing this from!, so i’m not in a position to take off the covers and remove the PCB to check myself. If you have access to your faulty heater, it might be worth, tracing the rear fan wires back to the circuit board where it connects, and then tracing the PCB copper tracks under the circuit board connector which feeds out to the fan, to see whether they go to some kind of IC, or a large resistor.

    If you are able to link to a couple of close up images of the topside and underside of the circuit board around the fan connector, then i’ll happily take a look and see if I can identify how the fan is controlled and what may be at fault.

    If you need to upload images, in order to link to them, then I recommend using

  21. Iain23 says:

    I live in France and have been running an inverter on basic pre-packaged 20 litre containers of fuel – “Mister Petrol” and others that are available from supermarkets and bricos, occasionally buying the heating fuel “pétrole” at the pumps at LeClerc, which I naively assumed to be the same stuff. The inverter has been running fine but started to fail occasionally with an E4 error – I cleaned out the residual fuel in the heater and bought a Mr Funnel after reading comments on this helpful site, but the errors still occurred and I bought a replacement heater (Japanese Tectro SRE 1330C at 200€ (about £150)) which is running without problems. I intend to try dismantling and servicing the old heater later to see if I can get it working again, but have a couple of questions……..

    [1] Is the fuel which is available at some service stations in France and described as “pétrole” what I was understand as paraffin or is it in fact heating oil?

    [2] All inverters carry dire warnings about not using last season’s fuel – but as stock rotation seems to be an unknown thing in France (it’s not unusual to see stuff for sale in supermarkets here well past its sell by date, including fresh foodstuffs) that I’ve taken no notice of these warnings. And as my inverter is an important source of heating for me and standard paraffin can suddenly disappear from the shelves in a cold snap leaving no choice but very expensive “no-smell” or Bio varieties, I carry a fair stock and could have 5 or 6 “bidons” left at the end of the winter. If I filter my fuel with the Mr Funnel, would there be any real reason why it would be inadvisable to keep fuel for an extended period – i.e. does making sure that any water (and dirt of course) is removed from the fuel negate the main reason that one is advised not to use old fuel?

    Thanks for an informative site

  22. admin says:

    Hi Iain23.

    I’m not too familiar with the fuels available in France, only what i’ve picked up from several Ex-Pat forums when researching these heaters. I believe that the “pétrole” served from the pump is standard domestic heating Paraffin, this is basically the standard domestic fuel used in Cooking Appliances, and Vented Heaters. Kerosene is the American word for paraffin, the fuels are the same, just the terminolgy which varies from Country to Country. I suspect the stuff you are buying from the pump, is exactly the same as we buy in the UK and known as 28 second heating oil.

    The pre-packaged Mister Petrol, will be what is often also known as C1 Paraffin or Premium Paraffin, this is basically exactly the same base fuel as the “pétrole” but has undergone a much more detailed refining process, which removes the odour and makes it burn a little cleaner.

    Basically, I use standard heating oil in both of my heaters, and have done for the last 4 – almost 5 years, and I believe that this is the same fuel as your “pétrole” sold locally. Yes, this fuel from the pump is not as refined as the pre-packaged stuff, but with EU regulations constantly restricting the amount of pollution, and reducing the sulphur content of all burning fuels, I can’t believe that there is still that much difference between them in actual use, other than a slightly stronger smell from the pump fuel.

    I’ve even read on a French Forum about owners running their heaters on a clean burning Isoparaffin based solvent called “Shellsol D60” , whilst I’m certainly not encouraging or advising you to do the same, it does show what a wide variety of fuels fall into the Kerosene / Paraffin family, and that you aren’t the only one straying from the recommended pre-packaged fuel.

    Fuel does indeed age, and how fast it ages depends on the environment in which its kept in. Water is the biggest contaminate, as the airspace above the fuel level in an underground tank or container can cause condensation which runs down the sides and into the fuel. The lower the fuel level in the storage tank, the more water its likely to absorb. Its only a small amount of water, given how much fuel an underground tank will hold, but its probably enough to eventually corrode or block the internal pump parts or injector inside these heaters. Dirt and Rust particles are also an issue, depending on how old the storage tanks are feeding the pumps where you buy the fuel. Happily the “Mr Funnel” will remove both water and dirt / rust particles.

    The problem with old fuel, is that it can eventually break down and encourage bacteria growth especially if it has a high water content, this bacteria would again, potentially cause problems with the burner and pump within the heater. However for there to be the chance of bacteria or mould growth within the fuel, it would have to be significantly more than 12 months old or stored in open containers or very poor conditions, so this is probably a very small risk. Domestic Heating Appliances such as Aga’s can be extremely expensive to fix, as are Farm grain dryers, both of which will burn “pétrole” so I would imagine the vendor would be facing quite large claims, or at least bad publicity if it was selling badly aged fuel already, so you should be re-assured that the fuel you purchase from the pump will at least meet any local regulations on fuel quality.

    As for keeping the Fuel in storage yourself. I would advise keeping the bidons as full as possible – limiting the amount of airspace above the fuel level, make sure that the cap is on tight. Keep the fuel stored in a cool dark place, and don’t subject it to direct sunlight. If you can get bidons which are dark in colour – such as blue or black, rather than white / clear it will limit the amount of light being absorbed through the container into the fuel, and so further reduce the risk of any bacteria growth, however if clear or white bidons are kept in a dark place, then they can continue to be used. Provided its stored in this way, I can’t see a problem with storing it until the next Winter season.

    There is no way of knowing whether using the pump based “pétrole” rather than the Mister Petrol is the cause of your E4 problem, we will never know for sure, however since one of my heaters has never been run on Pre Packaged fuel and is still burning as I type this on ordinary heating oil – years later, I think the chance is slim. If the heater is fairly old, and has been used a lot in the past then perhaps it was due for a cleaning inside it already. Certainly there is a comment above from another visitor, who states that his heater was used on nothing but the recommended pre packaged fuel and he still had E4 problems and his heater still needed cleaning, so problems do occur and these heaters do need cleaning even when used on the correct specified fuel.

    In relation to your ongoing E4 problem, I would suggest going ahead and following our Corona Servicing Guide, don’t forget to also clean under the burner too, where the injector is. (Another visitor commented that they found a build up of carbon in there too). I make it a routine to service my heaters in this way at the end of every season, even if its not showing any faults, and the time it takes to do this seems to be a reasonable trade off for the cost I save on buying standard fuel, rather than the expensive pre-packaged premium fuel.

  23. Iain23 says:

    Thanks, Admin, for a prompt snd very useful reply. The heater giving the problem is only a couple of years old but has had a lot of use, so I’ll give it a service some time and see where that gets me. My fuel is stored in a dark cellar under the house and mostly in opaque bidons. I’ll keep up with regular maintenance on the new heater and use the Mr Funnel……..

    Thanks again

  24. Joe says:


    I tried replacing the fuel and blowing through the fuel pipe but am still getting the e0 fail. Is it possible that transporting the unit with a little fuel in the bottom tank has got a sensor soaked in fuel somewhere in the bottom of the unit?.
    Many thanks


  25. admin says:

    Its usually a good idea to drain down the heater when transporting, or putting it away for the Summer. But if the Heater was transported upright, then I can’t see that it would have done any damage.

    Have you tried cleaning the Air Intakes on the back of the heater?. On my Corona 3016 heater there are two vents. One is the main metal fan intake, the other is a small round black filter just below the fan which can be removed by pulling it. If you haven’t done so already give both of these a good clean.

    How long does the Heater run for, before it gives the Error code?. Does anything happen with the heater just before the code is given – does the flame turn more yellow / orange rather than Blue in the Burner?, any unusual noises or smells?.

  26. Joe says:

    Hi thanks for the response and thanks for the advice on transportation .
    The heater runs for 8 to 15 seconds then cuts, it makes an obvious ticking noise during
    Running with a blue flame. After leaving the heater near a radiator to dry the heater started working for a day so I took advantage and burned the oil in the internal tank away . Now it back to e0 alarm after working for a day . lAst time this happened , when it started working it kept working , but il leave if near a radiator again For a few days and see if it clears it again.
    Keep you posted
    Many thanks

  27. wendy says:

    I bought a new inverter heater in dec 2015 my dog peed on the front it came up with e1 e2 e9 e0 i have changed the oil and cleaned the filters what else can i do

  28. admin says:

    I probably shouldn’t have read that whilst taking a swig of coffee since most of it is now over my laptop screen. But anyway…

    It would depend on where the pee went and was the heater on at the time?. You may want to follow the instructions HERE which has a step by step guide and a video which will show you how to strip down and clean the inside of the

    The first step of the instructions on the link above, show you how to remove the cover and access the inside of the heater, at this point it would be a good idea to check to see if there is any obvious signs of urine contamination on the main electronic circuit board (which is situated to the right hand side of the heater looking at it from the front). If there is no obvious liquid on the circuit board, then servicing it in line with the instructions in my guide may solve the problem, however if there is obvious liquid contamination on the circuit board then you will probably need to replace it. Urine is conductive and eventually becomes corrosive, so if it has run over the electronic components or across the copper tracks on the main board then it has probably caused immediate damage to it. You could try removing it to clean it, but the damage has probably already been done.

    Either way, the first thing that you need to do is remove the covers and gain access to the inside of the heater, to assess where the urine has gone and what it has affected. Once that has been established you should know the extent of the potential damage. Feel free to post back with an update.

    P.S I’ve not approved the post with your email address on it, only because this blog, like many others is visited every day by hundreds of spam bots, and they scan blogs in order to gather up visible email addresses from the internet to add to junk spam email lists.

  29. Michael Titterington says:

    I have been given a Inverter 6003 Model
    I was given such, knowing that there is an issue with the fixed fuel tank leaking. When there is fuel in the tank, there is a leakage into the small bund around the outer casing.
    I have had a very quick inspection by simply removing the rear and front outer casings. As yet I do not have full visual access to the tank area. BEFORE I proceed any further. The person who gave this to me. HAS used correct fuel. They noticed the problem after a user maintenance of draining the tank and with a clean lint free micro fibre cloth wiped out the ‘bits’ (not sure if rust or?). Upon filling with fuel, then it became apparent a short time later.
    Is this simply a case of a fuel pipe become loose/disconnected/damaged? Is this unit repairable? renewable? How do I get to this Where can I buy same? I’d really like to get this fire working, its approx 3.5 years old so no warranty

  30. admin says:

    Hi Michael

    I’ve never had to strip one of these heaters down to the internal fuel tank let alone remove it, so i’m unable to help with information on how the pipe connects to it, or the general layout, although all connections seem to lead to two openings in the top of the tank. I’m guessing one is for the fuel feed and one is the fuel level sensor.

    One both of my inverter heaters, the pipe feeding the inline pump is metal – probably copper, so it could connect to the tank feed using some kind of union.

    It is possible that the pipe union or connector is leaking, or perhaps a perished seal in which case, tightening or replacing the connector or even wrapping the threads with a bit of PTFE tape will probably solve it. However its also possible (but less likely) that the copper pipe has split also, in which case it will probably be easier to obtain a replacement feed pipe (The 6003 still seems to be in production so parts shouldn’t be a problem).

    Its also possible that the tank itself has split somewhere or corroded through a seam or weld, in which case depending on the location of the leak I would be trying to repair it first with some Automotive Petrol Tank repair paste or Epoxy Putty, rather than replacing the entire tank itself, as large component parts for these heaters can be VERY expensive, often costing a large percentage of the cost of a new heater.

    Until you actually find the location of the leak its a bit hard to advise on your best course of action, as there are three possibilities which i’ve highlighted, all with different remedies and scales of cost. However I can’t see why there wouldn’t be some kind of resolution to the leak, whatever the cause.

    Edit:- I have managed to find a Website of a Vendor in France who list and can supply a replacement fuel tank for the 6003 (but currently out of stock). As I suspected a replacement tank is very expensive, but more importantly it has an image showing where the fuel connectors and sensors are located. From the layout it does seem that it may have some kind of seal or gasket under where the pipes / sensors attached so you may be lucky and find that the joint just needs tightening or a gasket replacing.

  31. David says:

    I am having serious problems with a corona 5096 heater. I have been running it on kerosene heating oil this past two years with occasional E4 warnings.
    I serviced it last year and found everything spotless clean.
    This winter I am getting E4 and E0 codes along with smoke and a bad fumes. I dismantled it and the burner bowl was half full of a sticky brown thick liquid some of which had leaked down the air inlet pipe and collected in the inlet fan enclosure.
    I cleaned this out and restarted it and after some smoke and fumes it ran ok for a few hours. It stopped again accompanied by more smoke and toxic fumes. I stripped it down again and found that after just a few hours the bowl was starting to fill again with this sticky brown liquid.
    The kerosene I am using appears to be clean and I always use a Mr. Funnel.
    I notice the end of the fuel jet is partially burnt away where it enters the combustion bowl. Also the spray from the jet is more of a spurt rather than a high pressure jet. Is this pressure normal? Could either of these be causing the problem?

  32. admin says:

    No idea what would cause that, I religiously clean both of my heaters at the end of every season and have never come across anything other than the expected carbon and heat related deposits in or around the burner chamber.

    A quick search of the internet for anything to do with kerosene / paraffin / heating oil and a brown liquid / residue have also drawn a blank.

    The only thing I can think of, is that its perhaps partly burned fuel, if the broken jet is pushing fuel in far faster than the heater can burn it, then it may cause the problem you have described. I know that over fueling from injectors in a diesel engine can cause similar problems, so its entirely possible that its partially burned fuel albeit on a smaller scale.

    No UK Vendors bother to individually list spare parts on their website, but you can get a replacement injector jet nozzle from here. (The Corona 5096 is the same model as the 5006 sold in other parts of Europe and both seem to share the same parts, but you may want to double check fitment visually first on the website photo).

  33. David says:

    Many thanks for the help. I have been unable to find a jet listed anywhere online. I also think the damaged jet head is the cause of the problem. Have ordered one today and will update you when I receive and fit it.

  34. Paul grace says:

    I’m getting e2 ,stripped down cleared a big lump of carbon build up ,so bowl is now clean ,prior to working ok and e2 on start up it did blow a white dust on ignition ,any suggestions ,ps cleaned out tank and filter and replaced with clean fuel🤔🤔

  35. admin says:

    Hi Paul

    Did you check and clean the injector jet nozzle in the Bowl as per the post just above yours?, even if the nozzle is intact, it can still block with dirt, carbon and other debris. Its worth disconnecting the fuel pipe back to the pump and blowing it through, checking the integrity of the actual injector nozzle at the same time.

    Do you filter the actual fuel as you fill the tank?. It’s wise to do this whether you use the correct premium fuel or domestic heating oil as some have reported fuel related issues even when using the recommended fuel and fuel filtering removes not only dirt particles but also water contamination which these heaters can be very sensitive to.

    What is the actual model number of the heater?

  36. Ben amin says:

    Hi guys…bit the bullet today and cleaned my inverter heater today. still displays E0 ERROR..lights for a second and then piezo continues..puff of smoke…and out..tries to relight. Then off. I found the bowl to full of black crud..I mean loads. I suspect the jet to be the problem. Any ideas. Any help will be appreciated.

  37. admin says:

    Sounds like a similar problem to the comment which David made above, but sadly he has not returned to tell us whether the advice given worked, or whether he found another resolution to his problem. But the first thing I would do, if not done already is to remove the crud from the bowl, and make sure that the injector nozzle and also the injector pipe leading from the bowl to the pump is clean, and non of the crud has either blocked the jet or the thin pipe which feeds it.

    Failing, that then I would replace the actual jet itself, if you have the same model as David, then you will find a link to a replacement jet / pipe assembly for that model in my reply to him, if you have a different model, then a quick search on the same French site given on the link, may also yield a suitable replacement

  38. Jimmy Irving says:

    Hi all.I am suffering e4 errors with my5006 inverter.I have serviced it but to no avail.My problem is that the heater lights for a short while then the flame flares up yellow and the heater goes out.I have read all the info here but no one appears to have had this problem anyone have any ideas?Thanks Jim

  39. admin says:

    Hi Jimmy. Sounds like problems with combustion, at the time of servicing did you check the injector nozzle which injects fuel into the bowl for blockages?. Whilst you do this, its also worth blowing through the fuel pipe which runs from the fuel pump to the burner and is usually made from copper, others have reported blockages causing problems where they have been traced to either the nozzle or the fuel pipe.

  40. Jimmy Irving says:

    Hi thanks for that but yes I have blown through the fuel pipe,removed the flame sensor and cleaned it but it still goes out shortly after lighting ,so where can we go from there?Could the flame sensor have failed although it seems just like a bent steel rod and I wouldn,t it could do.

  41. admin says:

    Flame Rod’s can and do fail, i’ve replaced one myself in the Corona Heater some years ago, it’s the only part i’ve ever had to replace in any heater, although my symptoms were slightly different to yours in that the Error code was displayed when the heater came to ignite, it didn’t even attempt to light just bleeped three times, displayed the error code and switched itself off.

    Another possibility is the fuel pump, however that is expensive, probably too expensive to gamble on without a professional diagnosis.

    Problems which are not rectified by servicing and cleaning alone, can be very tricky to rectify and largely come down to elimination by the replacing of components, starting with the most likely first, or alternatively referring the diagnosis to a service agent.

  42. Jimmy Irving says:

    Thanks for that.I will try the flame rod first.I have tested the pump and it’s seems to inject ok.I did this by removing the pipe and then refitting it without putting the nozzle into the burner and switching on the heater and holding a can in front of the injector so I could actually see the fuel being injected.This might be helpful to others.

  43. Gracybfc says:

    Re Jimmy ,I’ve had exact same problem finally after two days appears to be 98% correctly working bar a dancing flame part yellow / blue ,I cleaned combustion bowl £ fuel pump etc all to no avail still e4 ,then I watched a video by an old boy on you tube ,who insists that your e4 code is your rods and the surrounding shroud with a gauze around it ,and he says and I did clean with some sandpaper ,and after I put everything back all is working correct bar the flame which isn’t the steady blue it should be

  44. Raymond says:

    Hi Guys,
    Im having a problem with my inverter 6003 heater ….
    It will run for hours but when it reaches the set temperature, after about 3 minutes the e4 fault comes up. The fault appears shortly after the heater reduces power.
    I have taken it apart and cleaned the flame rod and combustion bowl. The rod is about 2 mm from the bowl .
    Can anyone offer any help ?

  45. admin says:

    E4 fault is generally caused either by a failed flame rod, or a failing fuel pump. Unfortunately with no service manuals or service data available in the public domain for any of these heaters, its trial and error and a case of basic elimination and advice given by other heater owners in order to find the actual problem. The post above yours, also describes the E4 error as being related to the flame rod, and also gives one possible (and cheap) solution. I would try this advice in relation to gently sanding the existing flame rod to remove any carbon deposits and return it to bare metal, if this fails then a brand new flame rod may well be required.

    On a side note, when you cleaned out the burn chamber did you also check and clean the pointed injection end on the fuel pipe, where it sprays fuel into the chamber?. It might be worth checking this, removing the pipe from the pump and blowing air through the fuel pipe in order to remove any carbon (which can block the pipe.)

  46. Raymond says:

    Thanks for your suggestions … I have cleaned the rod with wire wool .
    I will have a look at the injection needle .
    I have watched it working today and its fine , provided u keep the tempertaure set higher than the room , but once it reaches the set temperature, then the flames die down over a few minutes until they eventually go out …. as soon as the flame goes out the error light comes on .
    This happens both on normal mode and eco mode.

  47. Cliff says:

    Hi I have been using the Inverter 5096 to heat a fish house for the past two years each winter. I began using it in October however five weeks ago it started cutting out showing an E4 fault for the first time. I have striped the machanicle side of the heater down many times and cleaned all the parts recommended however the heater continued to cut out showing the same fault, it would run for ten minutes or for a couple of hours. As the last couple of nights have been frosty, before going to bed I though I would fire it back up as it had cut out earlier, for some strange reason I picked a cloth up and wiped over the unit including the back. While wiping the back I caught one of the black sensor with the cloth pulling it away slightly so i placed it back where it was approximately. As there are two sensors on the back I repositioned the second one as well. The following morning I was surprised to see the inverter still on and for the last two days it has not showed a problem. Very strange, I can not help wondering if moving the sensors had something to do with fixing the problem. I was at the point of buying a new one. Worth trying it your self if you are having a similar problem where servicing the heater has not worked.

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