Truma D 6 E. diesel combi heater E122H fault

[Roberts82]

Chausson 2017. 718xlb
Our truma combi stopped working and showed an E122H fault. From the internet this appears to be a no diesel or low air flow fault.
After much hunting around to find the fuel pump we found the suction pipe fitted to a tee piece on the top of the fuel tank had one half of the tee piece snapped off. After a temporary repair the boiler will still not start. Over 10 resets and hard resets still no fuel. We checked for pulses to the pump and it appears there is no output from the boiler. In addition if we select water heating on electric the fault still appears and will not heat on electric. It seems strange that this fault code also stops electric water heating??
The suction pipe on top of the fuel tank is under the carpet under a hatch with a circular plastic cover protecting the top of the van sender unit. The snapped tee?? There is no sign anywhere of the second pipe or what it could possible used for or how in earth did it snap off. There is no sign of anything that could have caused this.
If you have any ideas we would be greatful.

 

[Okta]

Is it possible the pump damaged itself when running dry and is not feeding diesel to the boiler. Also the temporary repair may have left a point where an air bubble could form. I note from the installation instructions I found online that spaces in the fuel line where air bubbles can get trapped must be avoided. Have you managed to clear the fault code before trying it on electric water heating?

 

[Roberts82]

Is it possible the pump damaged itself when running dry and is not feeding diesel to the boiler. Also the temporary repair may have left a point where an air bubble could form. I note from the installation instructions I found online that spaces in the fuel line where air bubbles can get trapped must be avoided. Have you managed to clear the fault code before trying it on electric water heating?

Apparently if you reset each time you can get fuel through but takes about 8 attempts. However I will try to purge the line at the heater.
As for electric water heating I have even hard reset as well as remote reset but the fault still reappears on water electric only. It is still a mystery why a tee piece was use unless it was all they had and blanked off the spare, but then how in earth did it snap off?
Thank you

 

[AndyWill64]

I've always found Truma Customer Services very helpful for technical support. Suspect at they would at least tell you how to clear the fault, and maybe explain whether/why a fuel fault affects electric.

 

[Roberts82]

Hi. I emailed truma without much success. They ignored most of sequence of events, told me everything I already knew except could be the glow plug and suggested I visit a service centre.
The error code remains the same. There is no attempt to start the fuel pump ( no output from combi ). There is no attempt to start the combustion fan. The glow plug is not starting.
Thoughts are combustion fan should start first?
Then the glow plug then the fuel?.
The combi does exactly the same in electric water heat mode. Which does not use combustion fan, fuel pump or glow plug.
There is nothing clicking or running and about 30 seconds later the error code. All because it run out of fuel!
Not willing to change components unless verified as broken. Don’t want a car dealership that keep replacing bits until it works. Even a glow plug could set me back £200.
When it finally is fixed I will post the solution all over.
Many Thanks

 

[Geek]

Hi. I emailed truma without much success. They ignored most of sequence of events, told me everything I already knew except could be the glow plug and suggested I visit a service centre.

Speak to them on the phone.

 

[seanie]

Hi. I emailed truma without much success. They ignored most of sequence of events, told me everything I already knew except could be the glow plug and suggested I visit a service centre.
The error code remains the same. There is no attempt to start the fuel pump ( no output from combi ). There is no attempt to start the combustion fan. The glow plug is not starting.
Thoughts are combustion fan should start first?
Then the glow plug then the fuel?.
The combi does exactly the same in electric water heat mode. Which does not use combustion fan, fuel pump or glow plug.
There is nothing clicking or running and about 30 seconds later the error code. All because it run out of fuel!
Not willing to change components unless verified as broken. Don’t want a car dealership that keep replacing bits until it works. Even a glow plug could set me back £200.
When it finally is fixed I will post the solution all over.
Many Thanks

hi did you resolve? I have a similar 122 code with no luck of resolving. I didn't run out of fuel. and had little luck from Truma

 

[Roberts82]

Hi, I found out from chat on the Forum that if the combi is started ( attempted start ) 15 times and fails each time the PCB locks . This can only be reset by a service centre that has the diagnostic tool…………. First ring around as not many have it………….. secondly the main Truma UK centre has had my PCB a fortnight after the local(150miles away ) could not reset it with the diagnostic tool. I am still waiting…..
The whole fault was caused by a broken fuel pipe on top of the the vans sender unit. This in the Chausson is under the floor between the driver and passenger seat. A small elbow/ t piece that connects the combi fuel pump suction pipe the the fuel tank somehow had snapped. It simply ran out of fuel. Truma so far can’t remove the software lock . If you are under warranty definitely question the legality of them using software locks that only they can remove,,, sometimes!!! I will let you know when Truma get back to me and what they want for the so called repair they do.

If you are lucky enough to find a local agent make sure they have a diagnostic tool as even a correct lockout cannot be reset from your control panel only a diagnostic tool.
Best of luck.

 

[eurajohn]

Chausson 2017. 718xlb
Our truma combi stopped working and showed an E122H fault. From the internet this appears to be a no diesel or low air flow fault.
After much hunting around to find the fuel pump we found the suction pipe fitted to a tee piece on the top of the fuel tank had one half of the tee piece snapped off. After a temporary repair the boiler will still not start. Over 10 resets and hard resets still no fuel. We checked for pulses to the pump and it appears there is no output from the boiler. In addition if we select water heating on electric the fault still appears and will not heat on electric. It seems strange that this fault code also stops electric water heating??
The suction pipe on top of the fuel tank is under the carpet under a hatch with a circular plastic cover protecting the top of the van sender unit. The snapped tee?? There is no sign anywhere of the second pipe or what it could possible used for or how in earth did it snap off. There is no sign of anything that could have caused this.
If you have any ideas we would be greatful.

View attachment 71497View attachment 71498

I'm aware this is an old(ish) thread and no idea if you managed to fix it or not, but from the photo's I'd say that the fitting is a 90° elbow and the hole is from a rodent chewing it.

 

[Roberts82]

Hi, still not fixed. The PCB was sent away to be unlocked. The diesel pump has been replaced. Still getting the 122H error.
There is no attempt to start the fuel pump or the combustion fan. There is no volt drop at all on the supply when starting up so there is also no attempt of switching on the glow plug.
The fault which was all started by running out of diesel also stops the combi running on mains electric only????
Can not be exhaust vent flow as this can only detect a fault if the combustion fan is running!
What now? Take a two hundred mile trip to a service centre and take out a second mortgage?
No point in the nearest service centre as no one has a diagnostic tool.
I am now considering ripping it out and replacing it with a Chinese heater and a calorifier.
£50 to reset a PCB if you run out of fuel and you try to start it 15 times. That is a disgrace, shame on you Truma.

 

[Geek]

This is the risk you run by curing the symptoms without finding the root cause of the problem. My experience of Truma service was very positive, but you have to book to go to Derby. There are agents who are able to diagnose and fix Truma devices, but perhaps not all of them are good.

Thinking of a Chinese diesel heater? I've got one here thst you could have cheap. Only snag is that it stopped working after just a few weeks of gentle workshop heating.

No error codes, no apparent faults, but the pump won't run. Basically, they're cheap tat. How lucky do you feel?

 

[Roberts82]

I still do not have a working boiler.
There is no attempt to run the the fuel pump, fan or glow plug. The PCB has been reset and tested with no apparent error history other that it ran out of fuel.
My thoughts are there is a pre self safety check before anything runs which includes the mains electric heating side. No one seems to be able to answer that question, what does it check before anything is allowed to start that would give anE122H error?

 

[Geek]

I still do not have a working boiler.
There is no attempt to run the the fuel pump, fan or glow plug. The PCB has been reset and tested with no apparent error history other that it ran out of fuel.
My thoughts are there is a pre self safety check before anything runs which includes the mains electric heating side. No one seems to be able to answer that question, what does it check before anything is allowed to start that would give anE122H error?

Truma heaters work without mains hookup, so that shouldn't be the issue.

Have you tried telephoning Truma in Derby?