Citroen C5 2.0 HDI 110 Code P0101 Low Power

[PhoenixC]

I wonder if anyone can point me in the right direction for the fault on my Citroen 2002 C5 110 HDi.
Its a bit awkward to describe it feels as though there is no turbo boost below about 3000RPM and then its as though a switch is flicked and it takes of like a rocket (relatively speaking). Once there power is there if you keep your foot down and change up at around 4000rpm it accelarates hard in every gear, however if the revs drop to around 2500rpm, again its as though a switch is flicked and the power has gone and if that happens on a hill then unless you change down to gears straight away then the speed will just keep dropping until you are down to second gear.

I just got the Lexia software yesterday and the only stored fault is P0101.
The description for this is :-
For EDC15C2, this fault represents:
- Air flow not sufficient against expected value.
Check the EGR valve operation.
- Air flow too great or not sufficient.
Check the calibration of air flow meter. Also check for turbo hoses adrift or split.

The fault has been there since I got the car from my father a few months ago and doesnt appear to have got any worse (Its possible that the fault has been on for a long time prior to that as well).

Before checking the Lexia software I had already tried swapping the EGR solenoid for the boost solenoid. Running it with the EGR solenoid unplugged. I have checked the vacuum pipes for splits and blockages and all ok. Same with the intake and intercooler pipes. I have applied vacuum to the EGR valve and I can hear it opening and closing, same with the intake butterfly. I have checked to make sure there is no vacuum leak on the brake servo as well. I had been wondering if its actually a fault relating to the vac pump itself not being able to generate enough vac to pull the actuator on the turbo so I think I will have to get a vacuum gauge to check this out, but I dont know if I am looking in the right area or not.

If its any help this is what info that was stored when the fault had occured
ecu code p0101
speed 2506rpm
air flow reference value 576 mg/stroke
air temp 3 degree
inlet air flow 312 mg/stroke
turbo pressure 1412 mbar

The problem is there all of the time and it does not bring the MIL light on.
As soon as the fault is cleared it comes back again. I have been out in the car while reading the live data and boost pressure looks to be around 100mbar below reference until it comes on song. The MAF never reads above 300 until the power is there and then it jumps from 300 to 600.
I am still getting to grips with the Lexia software so not sure if there is anything else I should be looking for but any advice would be greatly appreciated.

[myglaren]

Your symptoms are practically identical to mine when it needed a new MAF.
Also indicated was the MAP but I never did anything about that - yet.

[DickieG]

As Steve says a duff MAF sensor IMO, take a read of my recent diagnosis of a Xantia HDi with a MAF fault here and you'll notice some similarities.

[centurus2400]

The symptoms are identical to the ones that I had on my C5 2.0 110 Hdi. . One replacement MAF later and all is well

[phoenixc73]

Well it looks like that could be it. I have just tried taking the air pipe off from the outlet of the MAF and drove up the road and the power is almost back to normal so I will order a new MAF tomorrow and hopefully that should cure it. Thanks for the advice.

[PhoenixC]

Well thats it sorted now. The air flow meter arrived on Thursday and I fitted it Thursday evening, its a totally different car, I forgot what it was like to have torque again. Thanks very much for the advice, its much appreciated.

[boristhespie]

Oh how we love this scenario.

[Treecreeper]

I am new to the forum and when I read this thread I felt a real sense of optimism, so I hope you don't mind me crashing in on the conversation.
My C5 is a great car, I love it but it is a love hate thing. It has cost me a small fortune but that's the nature of car ownership I guess. The current problem is something that has developed over time but currently the situation is pretty dire.
The turbo started to go really flat on the odd occasion, probably about two years ago. It only lasted briefly, returning to normal after releasing the throttle. I lived with that for various reasons. Not long ago my wife took the car out during a severe downpour and the following day it was as if the turbo didnot exist. Really lacking any acceleration or power, sometimes struggling to get out of fourth but sometimes, on the flat, feeling a bit more responsive.
There is no noticeable smoke and I can still hear the turbo. The economy seems to have got worse too.
After a while I realised there is a real burst of acceleration after about 3000rpm.
Having read this thread I thought I might have found a great answer to the problem. Having read elsewhere that disconnecting the MAF is a good way to diagnose whether it's faultyI tried it tonight. I took it to mean disconnecting the wire not the pipe. Unfortunately there was no difference.
Can anyone give me any further advice? Please, any advice. Not wanting to sound desperate here, I would love this scenario to be the right one!

[myglaren]

Welcome to the forum

Have you actually looked at the MAF?
I destroyed mine by having the wheel arch liner blow off.
The induction hose is in the wheel arch and was sucking up water and salt/sand/grit WHY and was in a desparate state.
The filter was sodden and ruined too, airbox full of rubbish and water.
Have a photo somewhere, anybody's guess where though.

That is a bit extreme but something along those lines could be affecting yours.
You were right to disconnect the electrical connection. If it makes no difference the MAF isn't working so it is in default mode.
Have you also seen this related topic?

I have heard but am very sceptical that you can disconnect the MAFthen run the engine at 3,000 revs for 2 minutes and it resets the ECU but I'll leave that for others to try.

[DickieG]

If you're able to get your car plugged into a Lexia diagnostic computer that'll take away the guesswork before spending money on a new MAF sensor, from what I've seen a duff MAF sensors readings increase in steps as the engine is accelerated whereas on a good one the readings move up in a smooth linear curve.

[Treecreeper]

Thanks for the welcome and the reply.

If the car is in default mode what does that mean if I try another MAF? Will a working MAF make any difference if it is in default mode?

DickieG, I am not sure what would cost more, a second hand MAF or a diagnosis? Your right though, it would be sensible.

Thanks.

[CitroJim]

DickieG, I am not sure what would cost more, a second hand MAF or a diagnosis? Your right though, it would be sensible.

A second-hand MAF is not to be recommended really.

A Lexia diagnostic could be free or at most, the cost of a pint or two. Have a butchers at the list here of members offering a Diagnostic check and see if anyone is near you...

[Treecreeper]

Thanks CitroJim.

Any advice regarding the default mode and trying another MAF off someone else's car?

[CitroJim]

Thanks CitroJim.

Any advice regarding the default mode and trying another MAF off someone else's car?

No harm in trying another MAF and generally they don't generate (at least on an HDi Xantia) a fault code so the car is unlikely to be in limp-home mode (which is what I guess you mean by default mode) so if the test MAF is good full performance should be restored.

[Treecreeper]

O.k., hopefully I will give that a go on the weekend, cheers.