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C4 HDi Anti Pollution (or Depollution) Error - Problem Solved

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Wed Dec 05 2012, 02:22am

Member No: #82
Joined: Jan 22 2007
Location: Hoylake
This is all I could find for PSA OBD Error Code P1639:
"Vehicle ID block corrupted or not programmed"

Mon Feb 04 2013, 02:10pm
Member No: #16928
Joined: Dec 20 2010
Location: England

I have a 05 C4 2.0HDI, 85k miles.

Had the troublesome "De-pollution System Fault" a couple of weeks ago, took it to main dealer and they diagnosed as an air inlet temperature sensor fail. Experienced some terrible avg. MPG readings (39 mpg). After over a week waiting for the part to come in, I had the sensor replaced today.

I was hoping to return back to the normal 45 - 50 mpg average readings but car is struggling to hit 38 average mpg now! Considered town and motorway use while attempting to get normal avg mpg.

Has anyone else experienced poor mpg returns during de-pollution fault (and/or post sensor replacement), or is this some kind of other problem? Perhaps the turbo to inter cooler pipe linkage as mentioned at the start of this thread?

Sat Apr 12 2014, 05:55am
Member No: #30089
Joined: Apr 04 2013
Location: Maldon Essex
Morning all.

My wifes 78k C4 Picasso 1.6 hdi 110 has a warning stating depollution system faulty. This has been coming on intermittently over the last few weeks, it will show, stay on a few days and randomly go off again.

There doesn't appear to be any change in performance, and it drives starts fine etc. I've noticed if its off, changing down and hard acceleration, or putting the engine under heavy load will instigate it.

I put it on an ODB2 reader, which showed code P0100, Mass or volume air flow A circuit (generic). When you check the other readings, it shows fuel system, EGR is ok. I'm thinking MAF sensor, but aren't sure, where is MAF on this vehicle?? Thanks in advance for answers.
Sat Apr 12 2014, 07:09am

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
A site search on P0100 brings up lots of information, including this: - Click Here -
Tue Apr 15 2014, 04:46am
Member No: #30089
Joined: Apr 04 2013
Location: Maldon Essex
Hi Dave

Apologies for the late reply, I thought I'd sent this Sunday.

Thanks for the response, having read it, I thought I would try EGR spray cleaner. Excuse me being a dullard, but which air intake should I spray it up, I would really appreciate some pic's?? I'm hoping to achieve cleaning the EGR and MAF at the same time.

The way it appears and disappears makes me think it is either dirty/sticking or a connection/wiring issue, I would have thought that had a component failed, it would be a permanent fault. Particularly as I have no noticeable drop in economy or performance, and it has not entered limp mode.

I'm not hugely mechanically minded, would this be something I could repair, or do you think it requires Citroen attention.

Thanks again for the assistance.
Tue Jul 22 2014, 02:34pm
Member No: #36585
Joined: Jul 22 2014
Location: Leicester
Hi there, I have a similar DPF fault on the dash. Occasionally it goes into limp home mode but most times it doesn't and performs no worse than normal other than to disengage the cruise control.

I had the light reset and codes read a few weeks ago and it came back with P0234 and P2566.

I fitted a new MAF sensor as an initial try (as I had a spare one handy). This was fine for about a week or so and then the light came back on again. I drove it as it was performing no differently and told my mechanic mate to have a look when I dropped it off for MOT the next week. When I fetched the car I asked him what the fault was and the light had gone off on its own when they took it in to test it so he thought I had fixed it. The next trip I took it on the light returned.

Am I looking at an EGR strip/replacement or is there something I am missing here?
Thanks in advance
Wed Jul 23 2014, 02:39am

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
You could have simply searched the site as the answers are there.

P0234 - Turbo Charger Pressure Sensor - Click Here -

P2566 - Click Here -

You should be looking at the Turbo pipework etc.
1 User said Thank You to Dave_Retired. for this Post :
 Giles (23 Jul 2014 : 16:38)
Mon Dec 14 2015, 07:47am
Member No: #26923
Joined: Aug 05 2012
Location: Suomi, Finland
I have issue with my car's fuel system.

Car Specs: Citroen C4 2.0 Hdi year of purchase 2008 in meter 203.000 km
So I have been getting these weird error messages from my car:

First comes Depollution system faulty and then comes Cruise Control system faulty. The Car eather runs rich (light blue smoke from behind) or it stalls. Most likely that it's getting too much or too little gasoline. As I am well prepared I have this OBD scanner dongle for my android phone, I manages to pull these codes our of the system:

meta-info header: Error Codes
file version:1
name:Trouble Codes
codes: P0087,
codes_p: P0087,
Error Codes
Fuel Rail/System Pressure - Too Low
PIDs supported [21 - 40] 00100000000000000000000000000000
Vehicle speed (Speed) 92 km/h
Intake manifold absolute pressure (MAP) 183.0 kPa
Calculated engine load value (EngineLoad) 96.86 %
MAF air flow rate (MAF) 54.71 g/s
Engine RPM (RPM) 1655 rpm
Intake air temperature (IAT) 7 °C
Engine coolant temperature (ECT) 77 °C
Fuel Rail Pressure (diesel, or gasoline direct inject) (FRP2) 10.0 kPa

Pending Codes
Fuel Rail/System Pressure - Too Low

Raw values
Error Codes 43010087;;
Panding Codes 47010087;;

Previus C4 2.0 Hdi that i owned for 2,5 years had the same issue wich was fixed by authorised dealership in warranty (used car, but I had 6 moths warranty). I think that they changed fuel pressure valve. Reason why I remember this is that at first they tried to make me pay for it. I disputed the case and they payed without issues. So is it the same fault this time or what?

I have set up a meeting with local indie garage for repair. They said that it would take 3 hours to fix the damn thing, So that's 200 euros well spend. The part in Finland costs 200 euros and I haven't managed to score cheaper alternative. I may even have to use authorized dealers part this time.

So any guesses if it in deed is the fuel rail pressure sensor? Too expensive part to just try ir out.

Some keep saying that the fuel filter might also be the reason but how could it be? If it get blocked I might understand the twiching on acceleration, but how does it run rich? My motor vechile inspection is due soon and I need this car fixed asap. Any guesses on the reason.
Mon Dec 14 2015, 07:53am

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
Did you click P0087

There is one possible answer there...
Mon Dec 14 2015, 07:56am
Member No: #26923
Joined: Aug 05 2012
Location: Suomi, Finland
So ... should I change fuel filter first just in case?
Mon Dec 14 2015, 08:45am

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
It's the obvious and cheapest solution.
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