picnmix

I have the same dilemma, I drive a C5 2005 mkII 2.0 HDI VTR and my wife had a C5 2008 mkIII 2.0 HDI VTR until recently. We traded in the mkIII a few weeks ago as more problems were looming even at a fairly low 54,000 miles. We already had an ABS brake problems (fault with wiring which runs from passenger's footwell) and air conditioning gas loss due to pipes failing fixed both under Citroen used car warranty. The power steering was still leaking after new pipes and seals (£550) failed to cure and it started cutting out with a message Low Oil Pressure (once dangerously on a dual carriageway) - the oil level and pressure were fine I think it's a known problem which would have required a new fuse box and the paint started to have a problem when washed at panel & door edges water would get between the paint and clearcoat and leave a dark patches - quite odd. I was also aware that the DPF might cause me trouble in the near future, although the same could probably be said for any newish diesel, but was a little worried that with the much stricter MOT emission test for a 2008 or later cars it could be more likely perhaps more difficult/expensive to fix. The ride and comfort in the mkIII were good I thought although this model was on steel springs and it's a fine looking car but what annoyed me (I'm 6'1") I kept nearly banging my head getting in - the roof line is quite low and one has to get in over quite a sporty raised seat edge. My wife was never that confident with the length of the car so is now happier with a Toyota Auris. I know my C5 mkII will not last forever and having tried the mkIII and personally found it wanting I don't know what my next car would be. For me it needs to be roomy and comfortable - perhaps a Skoda Octavia but I know I'd never be quite as happy as I am with my C5 mkII !

Thanks the best lead I have at the moment is from a Peugeot forum (same engine). This is the quote : "Hi everyone, I am an experienced independant mechanic. I work alot at HDI's. Basically what is happening is that your car is requesting regeneration assistance every say 400 mile or 600 KM, ie you will only experience the problem at these intervals. It will start the regen say 10 - 15 mins after starting car. During regen the car bypasses the intercooler. It does this by closing the top doser valve and opening the bottom valve. Your cars are closing the top valve but not opening the bottom. This chokes the car of air and to prevent stalling opens and closes the top doser. The car will rev up and down from 500 to 1500 rpm on idle and give out bursts of smoke from exhaust. it will also lack power and chug alot until it hits higher revs. The 3 things that can cause this is the bottom doser is broken (ie flaps about loose when hose is removed), the second is a vacuum problem ie leak from pipe etc and the third is a faulty solenoid which is at the bottom left on front of engine, 2 bolted togeather and they are both brown, i think the bottom doser is the back solenoid next block, i cant remember. If you pull vacuum pipe off top doser when the car is idling erratically it should let it idle smooth. It may not be safe to drive with it disconnected incase the dosers close for engine braking? Im not sure. "

I've got the same or very similar problem on my C5 2.0 HDI problem the best lead I have at the moment is from a Peugeot forum (same engine). This is the quote : "Hi everyone, I am an experienced independant mechanic. I work alot at HDI's. Basically what is happening is that your car is requesting regeneration assistance every say 400 mile or 600 KM, ie you will only experience the problem at these intervals. It will start the regen say 10 - 15 mins after starting car. During regen the car bypasses the intercooler. It does this by closing the top doser valve and opening the bottom valve. Your cars are closing the top valve but not opening the bottom. This chokes the car of air and to prevent stalling opens and closes the top doser. The car will rev up and down from 500 to 1500 rpm on idle and give out bursts of smoke from exhaust. it will also lack power and chug alot until it hits higher revs. The 3 things that can cause this is the bottom doser is broken (ie flaps about loose when hose is removed), the second is a vacuum problem ie leak from pipe etc and the third is a faulty solenoid which is at the bottom left on front of engine, 2 bolted togeather and they are both brown, i think the bottom doser is the back solenoid next block, i cant remember. If you pull vacuum pipe off top doser when the car is idling erratically it should let it idle smooth. It may not be safe to drive with it disconnected incase the dosers close for engine braking? Im not sure. "

Umm thanks - I think you are on to something with the DPF. I beginning to think the problem is sort of regular about every 300 miles I'm guessing suddenly starts and then is fine 10 or 15 minutes later as if it coincides with a DPF regeneration.

I'm having occasional problems (comes and goes at random) with lumpy running on my 2005 C5 facelift model 2.0 HDI 16v 138bhp with 45,000 miles. The symptoms when it occurs, are unstable idle (constantly reving up and down from 500 - 1300rpm), hesitation when accelerating and a lurching feeling when driving - it holds back and then suddenly goes. No warning lights or dash messages and no errors logged when checked with Lexia. It seemed possible that the EGR was at fault so the simple solution seemed a blanking plate. I chose the type if a small hole in centre as I was concerned that with this engine the management system might notice a totally blanked off EGR. This has improved things about 50% but its still happens and is very annoying when it does. So I think I'm on to something with it being caused by the EGR valve, with it perhaps sticking and staying open when it should be closed hence the partial restriction with the holed blanking plate helping to reduce the symptoms. I could replace/clean the EGR value but I'm thinking the problem could be back sooner or later. My question is with this engine (2.0 HDI 16v 138bhp) should I just fit a total blanking plate without the hole or would the engine notice and complain with messages and limp home mode? Thanks, Chris.