C5 Anti Pollution Alert

[garryd]

C5 ‘53 plate, 2.0 L petrol, Auto Estate

 

Not so much a new topic as a continuation of one I started last December on another forum. Then I had a starting problem where (occasionally) the engine would run rough, misfiring and not pulling; this would throw up messages all over the dash – ECM fault, Service fault, Anti pollution Alert, Cat Conv Fault. I eventually found a way of overcoming this by switching on ign for 20-30 secs before turning the engine over. This worked every time, so I lived with it temporarily, but I do like to have everything working as it should, and eventually I called the Citroen garage who do all my servicing.

 

They fixed it by installing 4 point plugs, new coil pack and updating engine management software.

 

All went well for a couple of months then one day returning from a shopping trip, downhill on overrun the Anti pollution Alert came up again.

 

Now this one has them stumped. They cleared the fault list and Lexia reported a faulty upstream Oxygen Sensor which they replaced and the engine started OK, ran on a road-test, but then threw up the alert every time the engine is started but with no suggestions from Lexia as to what the trouble is.

 

They’ve had the car for over a week now and still can’t find the cause.  

 

The MOT was due last Friday, but of course if won’t pass until this is fixed!

 

Any suggestions would be gratefully accepted (and prayers!)

 

:rolleyes: Garryd

 

 

 

[paul.h]

Welcome to the forum.

 

You would think the sensor that is telling the car there is something wrong would be identified by a fault code or out of normal range by its live data - if not then there would not be a problem. If you can get the fault list and codes from the garage and put them on here it may help with replies.

 

One thought to consider, was the upstream lambda sensor (oxygen sensor) that was installed done by a Citroen dealer using a Citroen part or a pattern part since pattern ones may not always work well ? The sensor wiring should also be checked for damage, it is well clear of the exhaust and the electrical connector is ok. On live data you should be able to see it switching about quite a bit. If the catalyst is working then the downstream lambda sensor should be showing a steady reading. Other things could include a temperature sensor fault, air flow meter fault - measured by a pressure sensor on the inlet manifold, maybe an overfuelling fault (injector), blocked air filter, air leak after the air flow meter, throttle body needs cleaning, egr valve needs a clean.

[garryd]

Thanks Paul for these helpful hints. I've spoken with the garage about some of these points , but I'll give them a call a talk it through with others that you've mentioned.

 

...Let you know how things proceed...

 

Regards

 

Garryd

[coastline taxis]

Get an emissions test done.  Think id be looking at a blocked/knackered cat. i take it that the car is running and starting well

[qman3428]

If the Citroen garage is saying there is no fault then  they should have no problem in issueing an MOT. After all they are saying nothing is wrong.

[garryd]

Thanks, gentlemen for these replies...

 

Since they have already done the MOT (and failed it on two unrelated faults to do with suspension) and picked up the Alert I think they must have done the gases test and haven't failed it on this one point as well. I asked the garage yesterday to confirm this point, and if in doubt to run the gas test again to confirm the cat is/isn't knackered. (BTW, they haven't suggested that it is.)

 

I'm  not sure about them being able to pass the MOT with an alert showing. There are so many new bits to the test now, there may be a clause somewhere...Last year my XM had a running-on problem with the fuel pump stop valve not closing, and showed a continuous ECM yellow light . I had to persuade them the MOT was to prove the car road worthy and safe (for driver/passengers, other road users and environment) before they agreed to pass it. But, yes, you have a point worth bringing up, since if the physical tests can't find anything, and especially if the gas test is within limits, then theoretically it isn't a hazard!

 

...Keep you all posted.

 

Garryd

[paul.h]

You can see the MOT testers guide on line on a gov.uk site. http://www.motinfo.gov.uk/htdocs/m4i00000001.htm

 

A quick look did not find anything on emissions warning messages causing a fail - but there are for the air bag and abs lights.

[garryd]

Thanks Paul H,

 

I knew about airbag lights, 'cos my Xantia had the light on for ages. Before I presented it to the MOT I took the switch apart (in the centre console) and cleaned the contact - job done. So the airbags weren't faulty! So much for the warning light...

 

... and therefore the MOT test.

 

Anyway, the garage assures me that it didn't fail for the Alert showing 'co the gases were alright. but for the suspension fault(s).

 

And a reply to Coastline Taxis:

 

Yes, the car is running OK, after the various shenanigans described in my opening Post. And I'm assured that a shot cat (that sounds like cruelty to animals) would come up as an error message both in car and on Lexia.  This used to happen before the misfire problem was fixed, but always following "Anti Pollution Alert" showed up. Since then I've not had the message appear (fingers crossed).

 

Thanks to both of you. I'll keep plodding on.

 

 

Regards

 

Garryd

[paul.h]

What are the suspension faults ?

[garryd]

Hello Paul H

 

A little matter of a leaking pipe on the F/OS, and another leak on the R/OS unit. Unfortuantely the Warranty Conpany (oops! a Freudian slip?) doesn't see these as "mechanical failure" so isn't inclined to cough up. Ouch! 

 

garryd. :(

[rickhough]

My 2001 2.0 HDi has done 238k miles and always gives the Anti Pollution (AP) fault message and EML lit after every oil change. A quick check on Lexia shows no fault codes and after around 20 stop and start cycles with 20 miles of driving in limp home mode (3k max revs) the ECU sorts itself out and the AP fault clears.

 

I can only assume that initial start up with fresh oil confuses a sensor somewhere, maybe initial oil pressure or something - but it is very odd that Lexia doesn't report any error codes.

 

This has been the case for nearly ten years of ownership and I've done about 150k of the 238k miles in that time with an annual oil change.

[garryd]

Hi rickhough

 

Nice to hear from you.

 

Glad you can live with the alert, though I don't like the idea of "limp home" mode for 20 stop/restarts! I've never had this even with the session of alerts suffered a year or so ago. For cold start, I now regularly turn on the ignition, count to 30 before I try to turn over the engine. This seems to work 99 out of 100 times. I did get the garage to change a lot of gubbins: new lamda sensor (twice), reprog software for Russian version (cos' the problem used to be mainly during the winter - but I don't think we get anything like their weather at the worst of times), new plugs (twice!), now have two prong versions).

 

As I say I rarely get this fault, though once I had to wait to pull out of my drive and the engine started misfiring, so I stopped, turned off waited and started again and it fixed the bad running but left an alert up. I took no notice and it went away after about 6-10 restarts.

 

Once or twice I've had an "Auto Gearbox Fault" flash up. Another was ABS Fault. just as I was driving to the MOT - heart in mouth I carried on, but the fault wasn't present when they tested the car and it flew through. But nothing ever came of either of these false alerts.

 

I must admit I don't take much notice of alerts any more, because they seem to be too easily promoted. Like one contributor said, in the days before digits, a drop of water would get into the fuel, the engine would cough, recover and drive on, none the wiser. Nowadays that same drop of water would raise a question in the computer parliament and the software would have to debate it for a month or two, before ignoring it.

 

Software is too broadbrush and causes more sleepless nights than I've got left!

 

 

Keep taking the Valium

 

Regards

 

 

garryd