Depollution System Faulty

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BKS
Donor 2021
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Depollution System Faulty

Post by BKS »

My C5 has an intermittent message something like 'Chance of depollution Filter Blockage' and 'Depollution System Faulty'.
Drove car for a mile no problems, stopped a couple of hours, driving back engine cut out, pulled over switched off, then restarted engine straight away, went about 20 Meters then engine cut out. Had to repeat till I got home.
Anyone any clues

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GiveMeABreak
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Re: Depollution System Faulty

Post by GiveMeABreak »

Basically what it says:

You have a Diesel Particulate Filter. These trap all the particulate matter in the filter, When it starts to clog, measured by differential pressure sensors, the engine ECU starts a regeneration cycle of the particle filter. Additive fluid is injected from the supply tank into the fuel tank whenever you add fuel. This additive helps lowers the temperature that the exhaust needs to reach from about 550 °C to 450 °C in order to burn off the accumulated soot and particulate matter.

The first stage in alerting you to a problem is when the filter is getting blocked up and the exhaust has not been able to reach the required temperature to regenerate. This can also happen when undertaking short stop and start journeys. If a regeneration cycle is interrupted (engine switched off) or it can never reach the 450 °C needed, then ultimately the filter will start to clog and this is where you will get the message coming up 'Risk of particle Filter Clogging' or similar.

There are some elements that cannot be burned off like ash, Cerine from the additive and engine deposits. Although the filters can last over 100k miles, they will at some point get blocked and will either need removing for cleaning or replacing. Depending on the level of blockage, they can also be cleaned on the vehicle using chemicals - many garages now offer this service including Halfords.

So when you get this warning, you are advised to drive 40 MPH minimum for 15 minutes or so to allow the car to try and regenerate. If this does not work, then the filter may be passed the point of being able to regenerate and you'll need to investigate whether it needs cleaning or not. Don't leave this though or it will prevent the car from running as the exhaust pressure will back up.

BKS
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Re: Depollution System Faulty

Post by BKS »

Thanks Marc, should have said we took the Filter off and cleaned it out,
I was wondering if the sensor could be faulty, getting desperate now, the car is dangerous to drive because of the frequency of the engine cutting out, cannot understand why it starts straight away after stopping logic would say it cuts out for a reason and shouldn't start again.

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GiveMeABreak
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Re: Depollution System Faulty

Post by GiveMeABreak »

Probably because the pressure dissipates once the engine is stopped - pressure build up is released momentarily.

It don't think it will be the EGR valve alone, as this shouldn't stop the engine running. It remains closed when starting anyway and gradually opens when the engine warms up. It shouldn't be a differential pressure sensor as that alone won't cause the engine to stop - but the engine ECU can put the vehicle into down grade mode (reduced power mode), so I think it has to be with a blockage. Is it possible you have damaged the filter when cleaning it? These have a special cement that holds the filter inside the casing and these are very sensitive. If they have been subjected to pressure washers or the like then they can break up...

BKS
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Re: Depollution System Faulty

Post by BKS »

We cleaned it out with cleaner and free flowing tap water, didn't use a pressure washer, but it wasn't blocked when we took it off to clean anyway, a Red Herring.
There are two connections that screw into the filter housing and bottom pipe, do you know if they could be the culprits, are they to do with the in/out pressure?

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Re: Depollution System Faulty

Post by RichardW »

Get some diagnostics to see what the computer is upset about - anything else is conjecture!

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GiveMeABreak
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Re: Depollution System Faulty

Post by GiveMeABreak »

The top pipe is the inlet filter pressure pipe and the lower one is the outlet pressure pipe, but these just tell the engine ECU what the pressure differentials are, so that the ECU can determine when to start a regeneration cycle. I would suggest getting it on a diagnostic to see what fault codes are being thrown up.

admiral51
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Re: Depollution System Faulty

Post by admiral51 »

Can i ask a silly question :)
You say the engine cuts out but you do not say how.
Does it cut out like turning the engine off with the key or does it lose revs and stall or does it do something like the accelerator pedal does nothing and the revs will not increase even if clutch down and accelerator floored ?
Just trying to understand the circumstances of the engine cut out.
Guess it has the double butterfly air doeser valve, it could well be mechanical and age/mileage related to the DPF message but it really does need a diagnostic session so we can get some fault codes.

Colin

BKS
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Re: Depollution System Faulty

Post by BKS »

Hi Colin
The engine just dies within a couple of seconds, start accelerating still in second gear next thing is power steering is gone. Have to switch the ignition to off before restarting as normal.

Marc and RichardW
Sounds like I'll have to get my hand in my pocket for diagnostics check, is it possible to hire or buy an ECU reader because I cannot get to Citroen.

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Re: Depollution System Faulty

Post by admiral51 »

BKS have a scout around your area, have a word with friends etc someone will point you in the direction of a trusted go to garage/auto electrician that will be able to do a diagnostic session at home.
Odd thought but do you have breakdown cover ?
They should have the proper kit and maybe able to provide you with a diagnostic session for much less, you just need the codes to start with if that makes any sense :wink:

BKS
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Re: Depollution System Faulty

Post by BKS »

Did get the AA out and they said fuel pressure was fluctuating, changed the pressure regulator on the pump, thought I'd cracked it after a mile of smooth running, stopped 2 hours then driving again and it was worse than it's ever been.

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GiveMeABreak
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Re: Depollution System Faulty

Post by GiveMeABreak »

Have a look at our member list with Lexia / Diagbox Software that are willing to help - details below and link.

At the end of the list is a link to a Google Map, showing the members' geographic locations and details. Just use the Private Message or Email links on the member's profile to contact anyone suitable.

List of Lexia / Diagbox Owners with Kits Offering Help

Bear in mind, although we update the list as often as we can, not all members are active on the Forum all the time, so it may take a while for a reply - and please remember current lockdown restrictions may make this difficult at present.

BKS
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Re: Depollution System Faulty

Post by BKS »

Thanks for the tip Marc
The nearest one 'Paul R' says he is still learning to use the system and is about 10 miles from me through the Mersey Tunnel, I would never make it,
I will try Mobile diagnostics for a solution.

Hell Razor5543
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Re: Depollution System Faulty

Post by Hell Razor5543 »

Within reason some Forum members with Lexia equipment will travel.

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Paul-R
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Re: Depollution System Faulty

Post by Paul-R »

BKS wrote:
12 Mar 2021, 22:05
The nearest one 'Paul R' says he is still learning to use the system...
Lol, that description is from about ten years ago with my original Lexia. Nowadays I have a full chip Actia and run Diagbox 7.58.