C5 X7 2.0 HDI 140HP

[maxc]

I have a C5 with engine code RHF 2.0 140HP. receiving fault codes P0087, P0088, and P0100. a tick black smoke when accelerating and poor fuel efficiency.
I have replaced, EGR valve, Mass airflow sensor, pressure regulator, Fuel, and air filter, But none of these has helped. I have checked the PDF it is clean enough.
I appreciate any help or suggestion.

[GiveMeABreak]

I think you are missing some parts of the codes:

P0100: Relates to your MAF (Mass Air Flow Sensor). The Air flow is above maximum permissible threshold. I would look at that first, as if the air flow is all messed up, then the engine ECU will start making incorrect air / fuel calculations.

Which may lead to the following faults, as it would be odd to have both low and excessive rail pressures at the same time. So focus on the MAF - either use a specialist MAF cleaner (and don't touch / damage the sensor wire inside - these are extremely sensitive). These cleaners are available as a spray and clean off all the muck without you needing to touch the wire. If this improves matters, then you may have your answer.

P0087: Relates to Rail pressure regulation: Rail pressure insufficient in relation to the reference value

P0088: Relates to Rail pressure regulation: Rail pressure excessive in relation to the reference value

[maxc]

Thank you, friends, I have first cleaned the MAF without any changes as a result then replaced a new one, still facing the same problems. Thick smoke, stalling a bit, poor fuel efficiency, lack of power. no problem with starting, good idling.

[GiveMeABreak]

It may take a little while for the engine ECU to adapt back to the changes. If no change, delete the fault codes go for a drive and re-check, then let us know if the same or other codes are appearing again.

[Gregor]

It's a common issue on all diesels from PSA, and can't really find the answer on any forum (including FORD, Mazda and VOLVO cars with same engines)... Now when it's cold outside, EGR stays always closed (is that normal?) and no black smoke on heavy accelerations at all. I also changed EGR valve and MAF but no effect.

[maxc]

It's a common issue on all diesels from PSA, and can't really find the answer on any forum (including FORD, Mazda and VOLVO cars with same engines)... Now when it's cold outside, EGR stays always closed (is that normal?) and no black smoke on heavy accelerations at all. I also changed EGR valve and MAF but no effect.

Hello Marc !
Today I did disconnect the Exhaust pressure sensor hose, All of the fault code and the smoke and stalling have disappeared, but I notice a lack of power it seems it affected the turbo. I wonder if you have any idea what might be the cause!? As I said earlier, The MAF sensor, EGR valve, And Fuel pressure regulator have been replaced, I have also replaced the Fuel and air filter too. Thank you for any suggestions/help. Best Regards/Max

[GiveMeABreak]

How many miles has it done? I'm also wondering about the DPF and whether that is getting blocked....

[maxc]

Hi !
The car has run 120000 mils, and I have checked the sot in DPF with a Diagbox which shows 17% which is long before it gets blocked. Regards/Max

[GiveMeABreak]

Hi Max - don't be confused by that. The soot reading just shows the soot loading at the time you undertake a check using the diagnostic tool.

The soot is what gets burned off during regeneration and this level rises - regeneration takes place - and then it falls back again, then the cycle repeats. The soot is not the same as the 'ash', engine oil deposits and Cerine elements that cannot be burned off during regeneration. It is these that eventually clog up the filter. At 120,000 MILES you are at the top most limit of the particle filter to be honest. This is about the time they need replacing or deep cleaned. Although at present it seems to be regenerating - but expect it to need attention shortly.

[maxc]

Hello Marc !
I have experienced clogged PDF on my earlier c5, The symptom is not the same, What I was experiencing the DPF problem the symptom was a huge shortage of power and the car could not run more than 60 mil/h at maximum speed. But now especially if I connect the exhaust pressure sensor line/hose, The power is as it has to be(perfect) but the codes P0100,0087 and 0088 come back plus stalling and a very tick smoke when accelerating. regards/Max

[RichardW]

If you're getting black smoke then the DPF is either broken up or not there, since it should catch that....

Black smoke = overfuelling, odd that connecting the exhaust pressure sensor makes it worse, is this in fact the manifold pressure sensor, and it is detecting a high boost pressure which is not really there, so dumping loads of fuel in? Can you see the live data on your diagnostic kit? What is the turbo pressure, and the exhaust DPF differential pressure.

[maxc]

Hello Richard !
First, I would like to thank you for your time.
I checked the turbo pressure on idling is 988 mbars and the exhaust DPF differential pressure is 28 mbars, I do receive a new fault code which is P2562.
Best regards/Max

[Gregor]

Marc my C5 is on a first DPF at 268.000 km with 76% ash and still regenerating btw 280-520 km. So 120.000 is not so much after all...

[GiveMeABreak]

Really depends on driving conditions / roads / average journeys / Speed etc Gregor, but the stated life is in those regions. I've also heard of others getting more out of them - but the shorter journeys are the worst.