C5 Depollution System Faulty

[McFrog]

Hi all,

Apologies for jumping straight in with a long list of questions before saying hello. Hello! I have a 2009 C5 with the comfiest front seats I’ve ever sat in in any car

In short before the rest of my long spiel, I’d be very keen to hear from anyone in Scotland with a Lexia you could kindly run on my C5 please? I live in Aberdeen but have a trip to Perthshire and the Borders next Thursday and Friday if my car can make it…

There’s a bottle of your favourite choice of tipple in it

I meanwhile have a Ross-Tech HEX-V2 if you, family or a mate have a VW / Audi / Skoda / Seat / or…Bentley that needs a scan in return.

So…

I have a poorly 2009 C5 X7 2.0 HDI 138 with one definite fault and a couple of niggles.

The “Depollution System Faulty” message came on when I started it to drive home last night, and the Engine Management Light stays on. Apart from feeling a little hesitant when starting it (which might be subjective / my imagination) it otherwise feels completely normal to drive. I stopped by the supermarket on my way home and it started without hesitation that time but the warning still came up and the light stayed lit. The car’s done a lofty 173,000 miles and I don’t have a note of the particulate filter having been changed by previous owners, nor the EOLYS 176 being topped up (the service book has some scribbled notes of Fuel, Oil, Pollen etc. next to various independent garage stamps at different times but no mention of particulate filter there, and as for more detailed receipts for work done these stop in 2013). I bought the car in Feb 2017.

I presume a Lexia would be the surest and quickest way to get a diagnosis of what has thrown the warning?

I’ve been meaning to track down a Lexia anyway to turn off the TPMS as the previous owner had a tyre replaced without re-fitting the sensor on that wheel, so it always throws up a “not monitored” warning after a couple of miles, which is mildly irritating but not so bad that I haven’t been too lazy or stingy to sort it.

And now another C5 owner has offered a cash sum for me to swap my 17 inch alloys for his 16s, but due to both taking the same 225/55 tyre profile (genius, Citroen) the rolling circumference would be 4.8% off so I’m expecting the speedo might then go a few MPH out. I understand that the new wheel size can be set in Lexia so that the speedo is correct again but when I phoned the dealer about this they cautioned that the change might, just might still cause problems for the ABS system, having confused the speed sensor. Is this a likely risk? I’d have that thought it would be fine so long as you had four matching wheels so that there weren’t differences between them in wheel rotation...

Any wisdom gratefully received

John

[myglaren]

Welcome to the forum John.
While I am unable to offer any specific advice as regards your C3 problems, have a gander at this thread for Lexia wielders in your area who may be able to help. A map link is at the bottom of the post.

If it is any comfort, my eldest daughter is on her third C3 and is quite happy with them - no persuasion from me there either.

[McFrog]

Ah, thanks Steve! Looks like a few options there for me

John

[GiveMeABreak]

Hi John

Regarding the wheel swap. The dealer is correct as it is the ESP system that might throw a wobbly. Exclusives were standard for 17 “ wheels with options for 18 & 19” fittment, so do need programming if you intend to downsize.

As for th pollution fault, hard to say at this point, you will need the codes read, however for this mileage you are at the life expectancy of the particulate filter. Your additive fluid should of been topped up before now so again that may be an issue.

Let us know what codes you get.

[McFrog]

Thanks Marc

So am I right that even if a dealer or a Lexia-welding forum member set the car to the new wheel size in Lexia there's a reasonable chance the ESP system still wouldn't like it?

John

[RichardW]

I don't see why the ESP should be confused - all the wheel size does is allow it to calculate the speed; all the ESP is interested in is the relative rotational speed.

The depollution fault is unlikely to be the DPF or the fluid - if it was either of these, then I would expect it to give a specific message related to this.

I'm in Lanark and Lexia equipped- I could plug it on Friday if you are anywhere near here on your trip. I've not done TPMS or wheel size changes, but assume they are via the BSI (which has the potential to go horrible wrong!) - but I can certainly read the fault code on the injection ECU.

[GiveMeABreak]

No that would be fine - as long as it knows the size of wheels fitted it will be fine afterwards. Can I ask why you want to downgrade these to 16" tyres incidentally?

I think there is also the possibility of the speedo settings too to factor in with the different circumference - a bit on all that here:
https://www.blackcircles.com/general/ty ... calculator

Also don't forget that the TPMS sensors can be had (Part 5430T4) for about £150 for four, plus the fitting, programming and activation of them should you want to keep the system operating - I have found mine has been very reliable and has saved me from running about on seriously under-pressured tyres when I had a bad seal on last tyre change.

[GiveMeABreak]

Yes, there should be specific warnings for the additive level and clogging - but not for other issues like the following, amongst others. so a diagnostic is a must.

• Differential pressure sensor
• Exhaust gas temperature sensors (downstream of the catalytic converter)
• Holed particle filter

[GiveMeABreak]

I don't see why the ESP should be confused - all the wheel size does is allow it to calculate the speed; all the ESP is interested in is the relative rotational speed.

No but with a smaller wheel size, surely it is going to affect the speedometer reading and also the odometer readings.

In this case, the following shows the variation between the original 17" wheels and the result of replacing these with 16" wheels:

Speedo reading km/h or mph	Actual speed km/h or mph
50	48
60	58
80	77
100	96
120	116
140	135
160	154
180	173
200	193

If anywhere - I would see if you can find the setting in the ESP ECU Richard

[RichardW]

Agreed it will give a false speedo reading

[McFrog]

Thanks all for the advice, really appreciate it

And thanks so much for the offer of the Lexia help Richard, that sounds perfect! I’ll PM you...

If it transpired that it was the differential pressure sensor, exhaust gas temperature sensor, holed particle filter or likewise, is there a risk of losing power, failing to start etc.? Would be unfortunate to get stranded mid trip.

Wheels-wise that’s reassuring about the ESP / ABS, and what I’d been figuring / hoping. The speedo problem was what I was anticipating so that’s a full house of us in agreement on that

I was happy enough with the 17s, it was more just that someone else wanted them more and offered me a bit of cash on top of the swap. With some more expense looming the cash could come in handy and I’m not precious about the cosmetic aspects as I find the C5 X7 distinctively stylish as it is…

John

[RichardW]

I put this on Diagbox for John today.

There's a permanent fault on 'Fan high speed control' (P0692) - but this is not putting the light on, as the fault came straight back without the light.

I suspect the one that put the light on is P2084 "Catalytic converter downstream temperature signal" Although it seemed to be working OK. Might just be one of those oddities that appears occasionally!!

It appears to be in fine fettle despite the 175k - plenty of additive left, and evidence that the DPF has been cleaned - and it looks OK from pressure drop and soot load. Only 2 previous service points recorded in the memory, which is a good effort! There were some suspension faults, but they all cleared and din't come back; one was about rear height sensor so I wonder if it's obviously gone doolally and been fixed, but the codes not cleared.

I managed to turn off the TPMS (I think - hopefully John will confirm!) - trawled all through the BSI and the TPMS ECU, but couldn't work it out, then found that you have to go in to Customer Configuration and accessories, then you can find the place to turn it off. There was also an option in there to set tyre size, but the wheel change is on hold at the moment, so didn't need to change that.

First time I've been in a C5 X7 I think.... it's rather nice!!

[GiveMeABreak]

Nice one Richard, so at least the filter isn't blocked then, so that's good news.

[RichardW]

I had a look around at the fault code, it seems that it may prevent regen; so it might need fixing if it comes back. New sensor is £125 mind you Part no 1618KP. It says the length is 1270mm so it would probably be worth tracing it back and checking / cleaning the connector.

[McFrog]

(Sorry for the delay in coming back after all the help on here. It has been one of those weeks but still no excuse…)

Thanks so much again for your help with this Richard! The scan and the explanations have been very helpful, and also good news too, especially on the DPF. And thanks too for looking further into the fault code, the part number and tactics

I’d driven 2 and a half hours to Pitlochry for the first part of my journey on the Thursday and I found that when I started the car afterwards the light and the warning message were both absent. That would have been its first long run since the first warning so maybe the rise in temperature might have helped clear it.

I can confirm there have been no more Tyre Not Monitored messages in the five trips since then (3 long, 2 short) so Richard’s Herculean efforts in finding the TPMS setting have paid off

I was pleasantly surprised at how few little faults came up in the scan. It seems to be an even better example under the scrapes and rust patches than I thought…

The C5 X7 is indeed very nice. To my own tastes, even nicer than my silver one would be a Mativoire Beige one like Marc’s

John