C5 II 2.0 HDI exclusive estate hesitating, 33 mpg.

[estateFan]

Hi,

I'm posting in the hope someone will be able to suggest a way forward.


Car History:

Citroen C5 II 2.0 HDI exclusive estate DW10BTED4 engine.
Now on 137,000 miles. DPF fluid topped up at 100,000 by myself and reset with Lexia.
DPF exhaust filter never changed. Always do my own service and repairs, oil change every 10,000 etc.


Symptoms:

3 weeks ago slight smell of diesel, sightly hesitant at low speeds (below 50), fuel economy bad at 33 mpg, should be 42 mpg.

Initial guess is DPF filter getting blocked, regen issues. Just realised I've not checked for diesel leaks because the smell is not there now. I will look later.

Bought a tank of diesel, did a 300 mile motorway trip. 70 miles up the M1, foot to the floor acceleration caused a DPF pollution message but after that the hesitating cleared and the car ran sweet for the rest of the trip. Next fill up showed 43 mpg. Problem appears to be sorted.

The Lexia showed P1198 "Fuel Flow regulating electrovalve Fuel flow too low" and P0087 "Fuel pressure regulation Pressure too low". I'm not worried about these codes as foot to the floor acceleration with a fuel filter that's never been changed are the likely causes. Lexia can't talk to the additive computer at the moment to check the regen figures, although when I topped up the Eolys a few years ago it could. Seems to be pot luck.

Cleared the codes.

It look's like lower speed ( below 50) hesitation (and possibly bad mpg) is back this week, but at motorway speeds the car appears to run fine (with possibly normal fuel consumption but can't verify).

Could it be DPF, EGR or something else.

Any advice would be appreciated.

Regards,
Tom.

[moizeau]

You can check the EGR in the actuator tests within Diagbox, just follow the instructions.
Does it hesitate when cold, hot or both, any smoke out the exhaust?

[GiveMeABreak]

Just a point of note - these MK II C5s had a separate additive ECU, whereas most later models have the additive function now incorporated into the engine ECU. It was well-known that these EAS ECUs often failed when the vehicles came to have their additive levels reset and often necessitated having to have the ECU replaced.

I mention this because you say there is no communication with the additive ECU. This could be affecting the additive injection - so if there is no additive being injected, then it means regeneration is unassisted and therefore the exhaust gasses need to be much higher for natural regeneration to occur (550° C instead of 450 °C), which may explain why a motorway run cleared the fault. Once you're back to town driving, the filter is liable to start blocking again.

[estateFan]

Thanks Marc. The additive was topped up 4 years / 37,000 miles ago and the Lexia was able to connect. But before that and then again recently I have connection issues. The symptoms do suggest the DPF is blocking up. I might try manually putting some EOLYS into the tank.

Hi Pete, hesitation is more noticable cold but does happen when warm, more around town below 50mph but also low trottle on the motorway. No smoking.

It looks like the car has reached end of life. It doesn't make sense to throw lots of money at it. Best car I have had in 40 years, £5000 for 107,000 miles in 8 years.

Thanks for taking the time to reply.
Tom.