Engine warning light comes on during acceleration

I have just bought a C3 1.4HDi 16v 2003 and found that the engine light comes on during acceleration at about 50 in fourth, or 70 in fifth, then power is reduced presumably by limp home mode. Error codes P0108 and P0237 are generated. Car can be reset by re-starting until next time it is asked to accelerate continuously for about 6 seconds. This may be temperature related as well as it appears to work fine when cold, and I think only happens when the second (or more) temperature light comes on. I've now tried a replacement turbo pressure sensor, but this does not seem to have helped. Does anyone have any ideas as what might be causing this. Many Thanks.

Hi MistyCottage, welcome to the forum.

My first thoughts would be to look very closely at the turbo itself and the associated pipe work to ensure there are no leaks of the boost (including the part on the right arrowed).



Picture thanks to Corkish and his XTR

Thanks for the reply Arfur. I have had the pipe work off of both sides on the Turbo last weekend, and found evidence of some oil coming out of the rocker breather and going though the turbo, and a light covering entering the inlet manifold pipe. I drained about 2 teaspoons of oil from the intercooler by inverting it for an hour. I was originally worried that it might may have come from the turbo itself, until I traced it back to the rocker breather. I have not investigated the EGR pipework as yet, but the turbo/pressure appears to be doing its job right up to the point that the engine light comes on.

MistyCottage wrote:I have not investigated the EGR pipework as yet, but the turbo/pressure appears to be doing its job right up to the point that the engine light comes on.

There are some pictures for the EGR removal here https://citroenc3owners.com/diesel-c3-ti ... -t289.html


It may be worth getting a lexia and looking at the turbo boost signal with live data. It may give you a bit more of an understanding on what's going on.

Some updates on were we are...
After changing the Turbo Pressure sensor, I managed to get a diagnostic tool on the car again, and although little seemed to changed in the symptoms of the car, I no longer have the P0237 code. When I first read the ECU this time, I had P0102, 219H/537 - undocumented code, P0108, P0401, P0261, P0267, P0270 & P0264. As the last 4 are the cylinder injectors open circuit, and the car had not failed to run at all, I cleared the faults to see which were still present, and the only one that came back during this round of testing was P0108, which my tester suggested is 'Fault inside ECU Atmospheric Pressure Sensor In short circuit to positive or open circuit'. On using the live data plotter, the graph for the pressure sensor was initially jumping between 976 and 988 mbars every few seconds. Then when I ran the car up the road, it locked on 976 for the rest on the test. (Actual measured air pressure on that day was 1008 mbar. Does this look like a real ECU fault?? Thanks

MistyCottage wrote:Some updates on were we are...
I had P0102, 219H/537 - undocumented code, P0108, P0401, P0261, P0267, P0270 & P0264... P0108, which my tester suggested is 'Fault inside ECU Atmospheric Pressure Sensor In short circuit to positive or open circuit'. On using the live data plotter, the graph for the pressure sensor was initially jumping between 976 and 988 mbars every few seconds. Then when I ran the car up the road, it locked on 976 for the rest on the test. (Actual measured air pressure on that day was 1008 mbar. Does this look like a real ECU fault?? Thanks

Trouble with the generic code readers is they can fail quite badly with manufacturer specific codes. The best tool to use on the C3 is Lexia which covers all the citroen manufacturer codes and gives proper descriptions and much more.

I think your P0108 description is a bit misleading, I would like to see what lexia makes of it.

If its the MAP, then check MAP wiring to ECU before pointing a finger at the ECU.

Have a look at https://citroenc3owners.com/petrol-citro ... -t859.html for P0108

Thanks for your thoughts C3CAR, but my C3 is a 1.4HDi 16V and as such I believe it does not have a MAP per say only the Turbo Pressure sensor. This has been changed and the error code P0237 disappeared and the realtime turbo pressure graph is now good. But the P0108 code remains. This code I believe relates to the barometric pressure circuit. The realtime graph for this sensor showed a reading jumping from 976 to 988 mbar every few seconds until the car was run up the road when it locked down to 978 mbar. As the barometric pressure that day was 1008 mbar, this suggests to me that I have a problem with the barometric pressure sensor. So the question is, where is this sensor located on my vehicle? Thanks.

This may sound really basic, but... have you changed the fuel filter?

Missing Lincs wrote:This may sound really basic, but... have you changed the fuel filter?

Sounds simple, but I always (and quite often, erroneously) assume that the basic servicing is up-to-date, because you wouldn't worry about faults if you skipped services? Always do the servicing, get someone else or do it yourself. Filters and oil are cheap enough.....

MistyCottage wrote:my C3 is a 1.4HDi 16V and as such I believe it does not have a MAP per say only the Turbo Pressure sensor.

Yes, the MAP sensor is the Manifold Air Pressure sensor,


Here it is on the 16v 1.4 HDi, seen right next to the EGR pipe

It measures the pressure in the the inlet manifold, but the turbo output is part of the inlet input.

MistyCottage wrote:But the P0108 code remains. This code I believe relates to the barometric pressure circuit. The realtime graph for this sensor showed a reading jumping from 976 to 988 mbar every few seconds until the car was run up the road when it locked down to 978 mbar

Well, the true barometric sensor is part of the ECU, but its not known to fail, unless the engine ECU/battery compartment is full of water? (its not common).

MistyCottage wrote:This code I believe relates to the barometric pressure circuit.

OK, but this is the first time I have heard of the ECU barometric sensor going faulty.

MistyCottage wrote:The realtime graph for this sensor showed a reading jumping from 976 to 988 mbar every few seconds until the car was run up the road when it locked down to 978 mbar. As the barometric pressure that day was 1008 mbar, this suggests to me that I have a problem with the barometric pressure sensor.

Your diagnosis is from a non citroen tool, and that had its own issues,

Would you disconnect the MAF and see how that upsets the figures you got on live data....

MistyCottage wrote: this suggests to me that I have a problem with the barometric pressure sensor. So the question is, where is this sensor located on my vehicle? Thanks.

Engine ECU has a barometric pressure sensor, but I would like to see that the MAF is not your problem or some wiring from the MAP to the ECU.

Thanks for your help C3CAR. FYI the diagnostic tool is a Snapon Versus unit that has auto identified the engine as a 8HY version, and identified the ECU as a Delphi C6 Part No:9653977080. I've attached the printouts for the initial up hill run. Before I replaced the MAP/pressure sensor, I was getting a similar turbo pressure (measured) graph but from time to time it would lock at a pressure reading giving a flat line, for a number of seconds. If that time exceeded about 5 seconds, then the engine light would come on, and economy mode started, until the car was restarted.

You suggested I disconnect the Mass Airflow Sensor, other than a change in the measured airflow and air intake temperature, am I looking for anything else? Thanks.