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

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Wed Jun 23 2010, 01:54pm
Car: 1.6Hdi, 110.

Symptoms: Get anywhere near 2500-3000rpm when cold (i.e. within 4 miles from a cold start) and the Computer would report an anti-pollution error and put me in limp home mode. I would have to stop the engine and re-start for the limp home mode to be cleared.

The Engine Management Light (EML) would remain on for a few days before clearing itself.

I used to have quite a lot of EML / Anti-pollution errors but a Engine ECU software upgrade cured them all, then recently this started happening.

I took it to my local authorised repairer (JS Auto Services - Basingstoke) and they diagnosed a problem with turbo boost pressure (I think, its a bit hazy now and my memory is not what it once was). Further inspection revealed a hole in a pipe.

This is the pipe that runs from the bottom of the inter-cooler to the right of the radiator across between the turbo and radiator and back into the turbo. Its mainly a rubber pipe with a metal bit in the middle where it crosses the radiator, the metal bit is welded to a bracket. It looks like the welds broke and left a hole (see pix below).

To prove the hole was causing the problem they put tape around the pipe and asked me to test drive it for a few days.
When the problem didnt re-ocurr they ordered a new pipe and fitted it.

You cant buy just the metal part you have to have the whole thing £116 plus about 0.5hr labour.

Im not suggesting that this is the cure for your anti-pollution error but, Im telling you the story just in case it helps.

Here is the pipe Im talking about:

Here is the hole that caused the problem couldnt quite get the camera to focus on the pipe):

5 User said Thank You to for this Post :
  (31 Mar 2011 : 14:20) , KenC (15 May 2011 : 10:53) ,  (11 Jul 2012 : 13:45) , CharlesDarwin (25 Oct 2014 : 16:49) , COLVERT (27 Oct 2021 : 13:49)
Wed Jun 23 2010, 02:01pm

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
That's an interesting one, made it a 'sticky' so others find it so they can check it out.
Fri Dec 03 2010, 07:14am
What does the limp home mode do in terms of your driving?

Makes me think back to Knight Rider, where Michael Knight can put KITT into Pursuit Mode. Not sure what that does unless the accelerator goes faster with less foot pressure
Fri May 20 2011, 02:58pm
can anybody help me citroen c4 2.0 hdi vtr+ depollution light on fault code p1693 any ideas please many thanks
Fri May 20 2011, 04:39pm

Member No: #82
Joined: Jan 22 2007
Location: Hoylake
This all I can find:
Turbo charge control circuit malfunction - SID 803 Starting and switching off of the engine controlled. Starting or switch-off requests absent or not valid.

Tue Jun 14 2011, 10:17am
Hi all, another 'anti-pollution fault' query!

I have a C4 1.4 sx 55 reg, and for about 6 months I've had the engine maintenance light on with the above notice. A friend told me to fill up with super unleaded and go on a good run (something about clearing the carbon build-up on the sensor?) and it should clear. I did this a few times and it worked first time but the warning soon came back!

Now I've invested in a U480 scanner and it picked up one error p0170 fuel trim malfunction (bank 1).

Can someone tell me if it just needs something replacing or cleaning? Will it be costly? I have an MOT on Friday, will it fail for that?

A symptom I can think of is very sluggish when first started.

Any help will be much appreicated!
Tue Jun 14 2011, 10:38am

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
error codes info: - Click Here -

Looks like it may be related to this: - Click Here - and you need to replace the canister electrovalve, details: - Click Here -
Tue Jun 14 2011, 02:12pm
Thanks for the quick reply C6 Dave! Will I need all 3 parts or just part 3 (£15.57). Cheers for the info, I think I'll get an indie to fit it for me.
Wed Jun 15 2011, 01:17am

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
Not sure but as long as the canister itself is OK then yes probably only requires part (3).

It's accessed by simply removing the wheel arch liner so could be DIY.
Mon Aug 29 2011, 05:29am
Member No: #11625
Joined: Nov 30 2009
Location: aberdeen
UncleZen, I found I had the same two little holes in the pipe, where the spot-welds had joined the pipe to the bracket.

To repair, I cleaned out any oil film from the inner, sanded clean outer pipe and inner surface of the bracket, then brazed (silver solder) the two items back together.

The brazed repair is superior to the original spot weld because it spreads the joint over a larger surface area, so is unlikely to ever fail.

Anyway, since repair, no more "Depollutions"

As per my post on this, I think the engine management does a check on the two flow sensors (upstream the turbo and downstream intercooler) and if there is a discrepancy, posts a Depollution warning.

1 User said Thank You to gmerry for this Post :
 BigJohnD (29 Aug 2011 : 17:14)
Tue Oct 18 2011, 03:16am

I have a c4 2005 1.4 vts coupe, have had a de-poulition light come on put a fault code reader on it has come up as po351- p0354 iginition coil .

replaced coil and fault has gone. next day fault came on again delete code and now lamba sensor fault now on.. replaced that sensor and fault has gone..
week later....

iginiton system fault code has come on..

has any one have any ideas before i get stung buy citroen main dealer prices..

Tue Oct 18 2011, 03:45am

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
Those 2 codes do point to the ignition coil which you say has been replaced?

The car needs hooking up to Lexia to see exactly what is happening, but it could be the engine bay fusebox or several other things
Tue Oct 18 2011, 06:53am
Member No: #20517
Joined: Jun 29 2011
Location: ireland
Wel lads i have the identical problem as above(very top of thread) with my 1.6hdi 110.
but it has only started coming up after i got my car remapped?
could my remap be the problem or is that possible?
Tue Oct 18 2011, 07:28am

Member No: #1
Joined: Aug 07 2006
Location: Northumberland
It's unlikely to be the remap itself and more likely to be a failing sensor
Tue Oct 18 2011, 12:04pm
Member No: #20517
Joined: Jun 29 2011
Location: ireland
what sort of sensor could it be?
and i will check that pipe tomorrow.
i just hope its not the remap because i love the extra power.
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