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Depollution fault |
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Ciaran
 
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  Member No: #3087
Location: . |
Hi guys, I've finally encountered the obligatory DPF issues. The C6 does do a some short journeys when at home, although I'm mindful of giving it a blast up the motorway at least once or twice a week. It has never exhibited any depollution issues before now. Ironically, the problem began after I'd spent 6 days driving around England, doing approximately 1,000 miles of fast motorway and A roads. Wednesday night, on the A55 into North Wales, (where I wasn't exactly hanging about because I was late for the ferry), I booted it entering one of the tunnels to overtake another car, and suddenly the display came up with 'Risk of particulate filter clogging'. This vanished as quick as it appeared so I wasn't too concerned, thinking the car had had a hell of a run all week, so there should be no DPF issues. All was fine, the message disappeared from the display, the engine was performing as normal and I continued at speed, the 50 miles or so to Holyhead port, making it just in the nick of time. However, after docking in Dublin, I started the car and was immediately greeted with an engine management light and 'Depollution system faulty'. I restarted and the message persisted. As I drove out of the port, I noticed a distinctive lack of power - limp mode I assume. The engine refused to go above 3,000 RPM, although eventually it did seem to regain some performance, although it was obviously still quite lacking its usual oomph. On Thursday morning I put some Wynns DPF regenerator in the fuel tank and stuck the Lexia on it. Fault codes as follows: P1531 - Pre/post heating relay circuit (had that since I owned the car). P2408 - Additive system (complaining about the fuel cap not being secured, which happened earlier in the day). P3008 - Air flowmeter signals P0299, P2279, P0069 - Turbo pressure signal Cleared the codes and rescanned, and they all vanished except P0069 - 'Atnospheric Pressure differential - Air leak after turbo' which came back. Interestingly, after a third scan, P1536 - brake pedal switch, also appeared and refused to clear. This morning I have ordered a new brake switch and harness, as it seems to be a common issue anyway, but just interesting it should appear out of the blue like that. Incidentally, one of the consequences of the brake switch being reported as faulty, is that regeneration of the DPF cannot take place, so I'm thinking the depollution fault might actually be a red herring, being triggered by the dead brake switch. Of course, the brake switch appears to be Ok, the brake lights work and I can disengage the parking brake and move the gear shifter. I had the car up the motorway about an hour ago and again it seems to be sporadically back to full engine performance, however I later stopped at a shop, and when I restarted, it felt like it was in limp mode again. Will be interesting to see what transpires, and whether the replacement brake switch, which arrives on Monday, will actually make any difference... I do like a nice mystery for the weekend. |
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e3steve
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   Member No: #1163
Location: Warsash, Hants & Palma de Mallorca, Spain |
A faulty switch — any switch — on the CANbus can throw up all manner of faults. The brake pedal switch is notorious, and also happened on our (now-sold) C4 Grand Pickarsehole EGS; usual ABS/ESP & Handbrake fault, plus ‘Gearbox fault - repair needed’ and, of course, no cruise engagement! It’s the same switch, incidentally... Depollution fault is usually an EGR issue, and my 2.7 has thrown that one twice and was nothing more than the valve(s) being stuck after the car had been inactive for over a month. Wynn’s EGR Cleaner fixed it both times, tout de suite... Incidentally, only using premium fuels and C2/C3 oils — e.g. Comma Protech 5W/30 — keeps the soot buildup to a minimum, although I understand you can’t buy premium in Ireland(?)  I’ll find a picture of some of what I extracted from the air distributor boxes and the mixer butterfly back in May 2013; 87,000 miles of mixed fuels, and probably had never been treated to premium diesel in its lifetime! The b l o o d y server won’t let me upload from my iPad, for some reason, even though I emailed the images to myself and compressed them down to 450KB... 
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e3steve
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Member No: #1163
Location: Warsash, Hants & Palma de Mallorca, Spain |
This is what the inside of your engine will look like if you don't use low-SAPS oil and premium diesel (a bit like the lungs of a smoker...): Rear bank air chamber, before vacuuming  Front bank air chamber, after vacuuming  This is what I scraped from just the mixer butterfly!  ...aside from the few bits of broken plastic and embrittled flexi conduits, of course. Since I took these pics in May 2013, my 2.7 was never again run on 'normal' derv except in an emergency! |
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gmerry
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 Member No: #21
Location: Scotland |
Hi Steve, I exclusively used Low Saps Oil, mostly supermarket diesel with maybe every 4th tankful BP Ultimate: My inlet throttle butterfly was probably worse than yours, very sticky. Low mileage too (that was about 60,000 miles) I'm not convinced that only using premium fuel would have made any difference: do the additional additives get recycled through the exhaust and EGR system without being consumed? Has anyone done any testing with a proper control? Best regards |
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Ciaran
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Member No: #3087
Location: . |
e3steve wrote ... A faulty switch — any switch — on the CANbus can throw up all manner of faults. The brake pedal switch is notorious, and also happened on our (now-sold) C4 Grand Pickarsehole EGS; usual ABS/ESP & Handbrake fault, plus ‘Gearbox fault - repair needed’ and, of course, no cruise engagement! It’s the same switch, incidentally... Depollution fault is usually an EGR issue, and my 2.7 has thrown that one twice and was nothing more than the valve(s) being stuck after the car had been inactive for over a month. Wynn’s EGR Cleaner fixed it both times, tout de suite... Incidentally, only using premium fuels and C2/C3 oils — e.g. Comma Protech 5W/30 — keeps the soot buildup to a minimum, although I understand you can’t buy premium in Ireland(?) Thanks for this Steve. I've been so busy with work lately and with the bad weather and dark nights I haven't had a chance to do anything with the car, but have now, finally, got around to changing the brake pedal switch. It's made no difference to the Depollution fault / limp mode. Interestingly, the fault is still there in PP2000 / Lexia, but it now reports as 'Intermittent' instead of Permanent. Its still reporting 3 permanent 'Turbo pressure sensor' and 'Airflow meter signals' faults as well. When I removed the old switch and harness, I noted the label on it was dated May 2013, so someone has obviously been here before. Funny, I have had the 'Handbrake faulty' and 'ABS / ESP system fault', ping up once or twice, several months ago (I think it was in July), but no sooner had it appeared than it went away again of its own accord. I put two cans of Wynn's EGR cleaner through the EGRs last weekend and there was a small improvement, in that although its still reporting depollution system faulty, it doesn't go into limp mode for about 50% of the time now. Previously it was permanently in limp mode. After the EGR cleaning, once it has been driven and warmed up a little, if the engine is stopped for a short time then restarted while still warm, it will usually then run at full performance with no limp. So I think you may be on to something with the EGRs being the potential cause. I'm going to try another round of Wynns this weekend, but if that doesn't improve things then I think its an EGR inspection job. Getting the time for that will be interesting. If I have to go there anyway, I might consider buying one of the blanking kits and closing them off... or is that just asking for trouble elsewhere? Regarding the premium diesel, yes it is unobtanium in many areas over here, although I know of a handful of places where you can get BP Ultimate. These are relatively out of the way for me but I make a point of doing the trip to get at least one tankful of it a month (car goes through an average of 2 - 2.5 tanks a month). So yes unfortunately the majority of the time its being run on the non-premium diesel, and I suspect the previous owner was the same, due to its scarceness. Is there any merit to adding the likes of Redex to the tank when forced to use the poor stuff, or is this unlikely to have any bearing on these kinds of issues? Cheers. Ciarán |
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Ciaran
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Member No: #3087
Location: . |
e3steve wrote ... This is what the inside of your engine will look like if you don't use low-SAPS oil and premium diesel (a bit like the lungs of a smoker...): Rear bank air chamber, before vacuuming Front bank air chamber, after vacuuming This is what I scraped from just the mixer butterfly! ...aside from the few bits of broken plastic and embrittled flexi conduits, of course. Since I took these pics in May 2013, my 2.7 was never again run on 'normal' derv except in an emergency! Holy [%*^#@!]! I suspect the inside of mine are probably going to be something like that, given the fact it will have been running on the non premium diesel the majority of time... Wow, that's shocking. |
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C6Dave
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  Member No: #1
Location: Northumberland |
Ciaran wrote ... When I removed the old switch and harness, I noted the label on it was dated May 2013, so someone has obviously been here before. ?? you don't remove the old 'harness', the new part supplied is an extension, unless of course it has been replaced previously so you changed the actual extension and not the harness. Only asking to avoid confusion for anyone else doing it. 
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Ciaran
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Member No: #3087
Location: . |
Dave-Retired wrote ... Ciaran wrote ... When I removed the old switch and harness, I noted the label on it was dated May 2013, so someone has obviously been here before. ?? you don't remove the old 'harness', the new part supplied is an extension, unless of course it has been replaced previously so you changed the actual extension and not the harness. Only asking to avoid confusion for anyone else doing it. Hi Dave, Yes it was the switch and extension not the main wiring harness itself. Ciarán |
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321dave
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Member No: #614
Location: Dublin |
Ciaran wrote ... Dave-Retired wrote ... Ciaran wrote ... When I removed the old switch and harness, I noted the label on it was dated May 2013, so someone has obviously been here before. ?? you don't remove the old 'harness', the new part supplied is an extension, unless of course it has been replaced previously so you changed the actual extension and not the harness. Only asking to avoid confusion for anyone else doing it. Hi Dave, Yes it was the switch and extension not the main wiring harness itself. Ciarán Hi Ciaran, I'm in the Peugeot 3008 today and I ran it yesterday on the motorway for a good clean out as it gets lots of city driving only. Today the deposition warning has appeared a few times and is going on/of the screen. It's not only a Citroen C6 issue as a general issue with Diesels and all PSA diesels that I have had did it. But after a few days it will go away generally by itself and next time the engine is booted hard it will return unfortunately. |
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e3steve
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Member No: #1163
Location: Warsash, Hants & Palma de Mallorca, Spain |
Ciaran wrote ... I've had the mixer butterfly off a couple of times since -- clean as a whistle!Holy s h i t e! I suspect the inside of mine are probably going to be something like that, given the fact it will have been running on the non premium diesel the majority of time... Wow, that's shocking. When you see all that crud, there in that box, it's fair to state that I was surprised that the damned thing ran at all!! The mixer butterfly's apertures were restricted to less than 30% of their original CSA... |
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Ciaran
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Member No: #3087
Location: . |
Thanks for the replies guys. It's actually quite funny that the depollution faults only seem to be reported when the car is being driven hard - i.e ideal conditions for DPF regeneration and the like. My C6 does about 70% city driving yet I'd never seen so much as a hint of a depollution issue until I hammered it that night in Wales. I'm fairly sure now my issue is EGRs rather than the DPF itself (although it could be both, just my luck!). I ran two more cans of EGR cleaner into them at the weekend, and again, a marginal improvement, it will now always be in limp mode from a cold start, but if its driven and allowed to warm up, on subsequent starts it now nearly always performs normally, whereas it was about a 50/50 chance before. I'm going to try the EGR actuator test with the Lexia later and see what that comes up with, but suspect its going to be a stripping out job. Maybe I'll just have to make a point of always going to get premium diesel now, even if it is out of the way, might have to fill a few containers... Thanks lads. |
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e3steve
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Member No: #1163
Location: Warsash, Hants & Palma de Mallorca, Spain |
Reading your excellent description, Ciarán, I can empathise. My 2.7 has done exactly that before now. I swear that it’s just the EGRs ‘sticking’. Bear in mind the level of c r a p that a DERV produces; the valves are forced to pass much of that, so it stands to reason that they’ll get crudded up from time to time. You’ve seen my evidence. Stick to premium diesel! Lower sulphur content, less soot production, less crud being handled by the engine’s clean-up systems... |
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Ciaran
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Member No: #3087
Location: . |
Thanks again Steve. I'm quite convinced its the EGRs now, so they're going to need a clean at least. From what I gather, access to the rear one is absolutely horrendous? I'm debating whether its worth buying one of the blanking kits and just blocking them off. I've read conflicting reports as to whether that's a good or bad thing. Obviously it would stop them blocking up, but it could also conceivably dump more [%*^#@!] into the DPF, and I also saw somewhere that the EGRs aid in preventing the turbos stalling at idle and such. Hard to know what to do for the best really. I think I'll be making the effort to get premium diesel all the time now regardless! |
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