C5 Depollution System Faulty

dcc236

New member
When I had my 08 C5 II, i just changed the diesel filter and all other filters when I bought the car. The build up of crud and calcification in the diesel filter canister taught me diesels can be pretty nasty. Now I just change the diesel filters on all our diesels annually.
 

Ken W

1000+ Posts
Is BP a better quality than say Shell or Caltex? What about independents like United etc? Should independents be avoided?
It was a load of Caltex that put my C5 into clogged fuel filter status. I always use Premium BP or Shell these days.
 
In my experience it is not just a case of what goes into the engine ( ie clean fuel that is able to be well filtered . meaning regular filter changes ) but what comes OUT. These things are not commuter friendly in that the auto seeks to be in the highest gear possible to keep revs low and assist fuel consumption but that means the engine and exhaust rarely gets really usably hot. Notice how long it takes for the OIL gauge to reach operating temperature. It is a lot longer than the water temp. A forced regeneration makes the entire exhaust system and the DPF get really hot and burn off the accumulated deposits. It is designed to do so. In my case I had stupidly dosed the fuel with a diesel injector cleaner and went to Europe for a while, as the result I suspect some chemical cleaning occurred .. and when pressed back into service after standing for a couple of months several "depollution system faulty" messages appeared over the following weeks until the car could be given a good hard hot run. The old fashioned "Italian tune up" cured the "commuter blues". My son was running a Mitsubishi Colt Ralliart at the time, and the multi brand service dealer was also the local Peugeot service centre. Discussion with the tech people revealed many of their Peugeot customers cars were not getting through new car service intervals without needing the diesel fuel filters replaced. They of course were blaming the fuel supply at the pumps, but I suspect it was equally the style of commuter usage that is not suited to diesel engines no matter how physically and chemically strangled the exhaust system may be to appease the Euro 3,4,5,6 legislation. Note the evolution to AdBlu systems that only appeared in the very last of the C5s.
The HDI engine really likes a good hard hot cleaning run, the sort that used to make exhaust pipe deposits white back in the days of leaded petrol.
 

dmccurtayne

Member
In my experience it is not just a case of what goes into the engine ( ie clean fuel that is able to be well filtered . meaning regular filter changes ) but what comes OUT. These things are not commuter friendly in that the auto seeks to be in the highest gear possible to keep revs low and assist fuel consumption but that means the engine and exhaust rarely gets really usably hot. Notice how long it takes for the OIL gauge to reach operating temperature. It is a lot longer than the water temp. A forced regeneration makes the entire exhaust system and the DPF get really hot and burn off the accumulated deposits. It is designed to do so. In my case I had stupidly dosed the fuel with a diesel injector cleaner and went to Europe for a while, as the result I suspect some chemical cleaning occurred .. and when pressed back into service after standing for a couple of months several "depollution system faulty" messages appeared over the following weeks until the car could be given a good hard hot run. The old fashioned "Italian tune up" cured the "commuter blues". My son was running a Mitsubishi Colt Ralliart at the time, and the multi brand service dealer was also the local Peugeot service centre. Discussion with the tech people revealed many of their Peugeot customers cars were not getting through new car service intervals without needing the diesel fuel filters replaced. They of course were blaming the fuel supply at the pumps, but I suspect it was equally the style of commuter usage that is not suited to diesel engines no matter how physically and chemically strangled the exhaust system may be to appease the Euro 3,4,5,6 legislation. Note the evolution to AdBlu systems that only appeared in the very last of the C5s.
The HDI engine really likes a good hard hot cleaning run, the sort that used to make exhaust pipe deposits white back in the days of leaded petrol.
Regardless a 7 year 60 k fuel filter is the problem here poor servicing and very poor diagnostic from central coast euro
 

jya

New member
My 2.0 litre C5 X7 2010 has been indicating the same 'DEPOLLUTION SYSTEM FAULTY' message but doesn't always appear.
When it did appear, engine even stalled a couple of times.
I noticed it started to do it after I had just changed the high pressure fuel pump gasket as it was leaking oil, down behind the engine (RHR). Coincidence? May be.
Filter hasn't been changed in 2 years so now due. Hopefully problem will disappear.
How do I prime the system after changing the diesel fuel filter?
 

seasink

1000+ Posts
There's a bleed screw and a rubber priming bulb. Open and pump. When you get a flow of fuel, close the bleed and turn the engine over to finish the job. It will start when the flow is good.

When you change the filter check for water in the housing. There is a drain at the bottom if needed, with a plastic drain hose. Put a glass jar under it.

There are many errors that trigger the depollution message; you need an OBD code read.
 
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jya

New member
Thanks seasink!

I have just found this YouTube clip from a fellow in Greece.
Seems to be a comprehensive enough video.



 

jya

New member
Successfully changed the filter.
Couldn't see any evidence of water in the bottle after draining. Did see some gold coloured filings in the sump of the filter bowl...
Only ran the engine for a few minutes but unfortunately the 'Depollution System Faulty' message remained. Runs normally otherwise.
Will have to go to one of the locals to read some codes.
I'm not an expert but sounds like a fuel pressure regulator or fuel pumps but who knows at this point.

Above clip link I posted was helpful but not for my RHR engine.
 
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Armidillo

1000+ Posts
Don't panic... These messages don't disappear immediately (unless you delete them with an appropriate code reader). Just drive it. After several restarts the message should disappear. If not, then find a trustworthy mechanic who not only can read the codes, but knows how to interpret them.
 
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jya

New member
Update:

Local mechanic found the fault code was for a faulty EGR valve.
What usually happens to the EGR valve if anyone knows. Is it a common problem?

I think I may need to invest in a diagnostic reader..
 

seasink

1000+ Posts
Fairly common on the RHR.

The RHH engine has a different EGR setup on the front of the engine. Exhaust gases have a passage through the head.
 
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