C5 De-pollution faulty warning after difficult starting

[rogerfry]

Advice needed! My C5 1.6 HDi 56 plate has twice shown the De-pollution system faulty warning. Each time it was after cocking up starting the car and stalling, then having to floor the accelerator to restart. The first time the warning cleared after a couple of short drives. This time the light won't clear despite 600 motorway miles. The service history indicates that it has passed the 85k mark without replacing the Eolys fluid as the service manual indicates, so is it simply a coincidence that the light has come on after these mis-starts and should I go for the servicing option or adding a cleaner, or did flooring the accelerator do something specific which indicates another approach. Any advice appreciated as I realise this is a hugely complex and potentially costly area of maintenance, and don't want to spend unnecessary money.
Roger

[RichardW]

Hi Roger

It should never be required to floor the accelerator to start a diesel - they don't flood like petrols. The fact that it struggled to start is pointing at some problem, it should just crank and fire whatever. No option I'm afraid, but to get it on a diagnostic computer (Lexia) to see what it's upset about - where abouts are you, there might be someone nearby that's got one that can look over it for you.

[jakesmydog]

Hello Roger
I had the same problem on a C4 1.6 HDI I had. What I did was check the fault with a fault code reader,( £10 off Ebay) put those in Google and found it was a blocked fuel filter bought another off of Ebay for £15 have not had any problems since. Nothing to do with the DE-pollution but it was that light which kept coming on, hope that helps.
FR

[citroenxm]

Hi..

I just hope your problem is not what ive just had on one of these hatefull 1.6 hdi things..

http://www.frenchcarforum.co.uk/forum/v ... =3&t=45298" onclick="window.open(this.href);return false;

Good luck..

[rogerfry1]

People might like to know how this was resolved. Basically it was all about a tiny air leak in the fuel lines. The clue was in the symptom that the car would start immediately then stall and then only restart after much cranking. After that the car was perfectly happy running apart from showing the warning light.

What was happening, with hindsight, was that fuel was available at the injectors but quickly ran out because an air bubble had been created further back along the supply line. The problem was at first only intermittent but over 4 months got so bad that it happened at every start up. It was worst when the car was parked facing up hill. Each time it happened the anti-pollution warning light would come on, but this was a bit of a red herring. The code merely gave "Low fuel pressure".

A very patient and persistent repairer worked through some obvious places where air might be getting in without curing the problem, then eventually found a tiny seal in the connector to the fuel filter to be the problem. He couldn't obtain a replacement seal without buying a whole set of fuel lines, so improvised a a different connection altogether.
This was a nightmare to diagnose, as after each attempt at a solution he had to leave the car for a while, in an uphill position, to see if air was still getting in, but seems to be fixed now.
Hope this might help others with similar symptoms.

[Hell Razor5543]

That engineer might be worth putting the Recommended Garages section.

[citroenxm]

Thats an interesting and VERY worth while diagnostic.

It ALSO shows that the Generic "Anti Pollution Fault" is NOT always to do with the Cat or DPF in the exhaust..

Ill tell you another one involving a 1.6 hdi 16v engine in a 206.

Driving along then suddenly the above fault... and stalled car.. However, would startup again.

Anti pollution fault showed.. Lexia said high pressure ref AND the clue, Slow Fill rate..high pressure system.

So, after suspecting a pump fault and still having it.. what I did notice the Squeese primer ontop of the engine was slow to fill..

On the 1.6 the Squeeze Bulb is AFTER the fuel filter, unlike older XUD engines the fuel filter was after the primer. Anyway, changed the fuel filter and the fault WENT AWAY! The fuel filter was so blocked the fuel pump couldn't pump enough through and so threw a fault out!

The reason for blocking fuel filter? The 1.6 uses an complete unit type filter, one where you swap the WHOLE unit not just the filter and they are 29 quid a time PLUS VAT..

[myglaren]

It ALSO shows that the Generic "Anti Pollution Fault" is NOT always to do with the Cat or DPF in the exhaust..
The 1.6 uses an complete unit type filter, one where you swap the WHOLE unit not just the filter and they are 29 quid a time PLUS VAT..

Interesting Paul. I bought a full set of filters today - only taken six months to get to the motor shop.

I started to change the fuel filter - usually about a five minute job, gave up after about forty minutes, couldn't shift the sealing ring.
Changed the air filter, then the pollen filter, which was a bit of a shock as all there was of the old one was:

Someone couldn't be bothered with a new one so kicked the old one to bits. Anyone's guess how long it has been like that, before I bought the car anyway.

When I packed up I saw the new fuel filter was of the type you describe but my total bill was £29, far less than the last set I bought.