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Citroen C3 1.0 2003 - CAT aging fault, code P0420 #

Posted by Alf Cox on June 19, 2011, 8:11 pm

Year of Manufacture *: 03
Engine Size and Code *: 1.4
( Optional ) Scanner Used: solus pro
( Optional) Fault Codes: p0420

Hi

Vehicle came in with launch diag printout with code P0420 cat aging permanent, I changed cat cleared code but has come back with same code. On checking live data did notice bank 1 sensor 2 is reading consistantly high 0.6-0.8 could this be leading the ecu to conclude a cat fault, or it is logged as a permanent code and my solus wont clear it.

Many thanks

Alf

Re: citreon c3 cat aging fault

Posted by aidan birley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on June 19, 2011, 10:01 pm, in reply to "citreon c3 cat aging fault"
Aidan Birley

Hi

What make of CAT was fitted ? After market cats have a poor success rate !

what are the 4 x exhaust gas readings at idle and cruse ?

can you scope pre & post cat sensor preferably together ?

Does that post cat reading change on acceleration and over run ?

sorry questions not answer.

cheers Aidan

Re: citreon c3 cat aging fault

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on June 20, 2011, 8:44 am, in reply to "Re: citreon c3 cat aging fault"
Mark Carter

Hi Alf,

That fault code can be logged for lots of reasons.

What diagnostic tests were carried out to prove/surport the fault code prior to fitting the new component?

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: citreon c3 cat aging fault

Posted by Simon Dean <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5221' width='330' height='300' border=0 style='border:none;'> on June 20, 2011, 9:24 pm, in reply to "Re: citreon c3 cat aging fault"
Simon Dean

Hi Alf,

Software issues,update via dealer the engine ecu.
Reset adaptions and monitor vehicle.
If code re appears fit gen cat,also would recommend oxy sensors replaced as best practice.

HTH
Simon

Re: citreon c3 cat aging fault

Posted by alf cox <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3079' width='330' height='300' border=0 style='border:none;'> on June 20, 2011, 10:08 pm, in reply to "Re: citreon c3 cat aging fault"
Alf Cox

thanks for the replies folks unfortunately customer had to use vehicle, it will be back later in week will post details when i have them.
thanks again

Re: citreon c3 cat aging fault

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on June 20, 2011, 10:42 pm, in reply to "Re: citreon c3 cat aging fault"

Hi Simon

Replacing both O2 sensors as a matter of course, sounds a bit over the top to me.

I know that we shouldn't be over concerned with costs, but rather make sure that the repair is correct, but often a quality catalyst will cost around 400 quid & then there is the fitting.

If we were to replace the O2 sensors routinely too, then the car will most likely be written off.

Where do we stop? Oil & filters, spark plugs, MAF sensor etc etc?

Having said all that, we do need to be sure that there isnt a fault elsewhere. I wouldn't like to spoil a nice new catalyst, by over looking an underlying problem.

Better to test & identify the cause I think!

This is a deep topic isnt it!

Re: citreon c3 cat aging fault

Posted by Dave Mittell <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3220' width='330' height='300' border=0 style='border:none;'> on July 6, 2011, 1:46 pm, in reply to "Re: citreon c3 cat aging fault"
Dave Mittell

Remove the post cat sensor and tie it up under car where heat cant damage anything. Plug the hole in the exhaust with an old sensor or something. reset codes and see what the post cat sensor is reading or if fault reappears should be reading fresh air therefore will lead the ecu to think that the cat is working efficiently. This will rule out the sensor. If the front O2 sensor is reading correctly and there are no other overfueling issues carry out emmissions test to see what the cat is doing if readings are high the cat isnt too hot. Find that the cheaper cats take a long time to warm up and arent as efficient causing the post cat sensor to pick up a bad cat reading on warm up.

Re: citreon c3 cat aging fault

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on July 6, 2011, 8:15 pm, in reply to "Re: citreon c3 cat aging fault"
Mark Carter

Hi Dave,

Can you explain to me how this works;

>>> should be reading fresh air therefore will lead the ecu to think that the cat is working efficiently.<<<

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: citreon c3 cat aging fault

Posted by Darren Cotton <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1876' width='330' height='300' border=0 style='border:none;'> on July 24, 2011, 11:02 am, in reply to "Re: citreon c3 cat aging fault"
Darren Cotton

Dave M

Got to ask the same question a Mark....

If the rear sensor is measuring a high O2 how does that make it efficient?

I don't know why after all these years techs are changing O2 sensors for this fault code, P0420 is what it is, "cat efficiency" simple test scope front and rear sensors engine warm, fast idle....

and all will come clear....

Darren

Re: Citroen C3 1.0 2003 - CAT aging fault, code P0420 #

Posted by alf cox <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3079' width='330' height='300' border=0 style='border:none;'> on July 24, 2011, 7:37 pm, in reply to "Citroen C3 1.0 2003 - CAT aging fault, code P0420 #"
Alf Cox

just an update guys. vehicle eventualy came back in with mil lamp on,checked codes which were:-
p1336 phase detection.
p1327 high combustion missfire on several cylinders.
p0300 random multiple missfire

code p0420 cat aging was not showing i did clear code a second time before customer took vehicle away so i guess over time it reset adaptation, also on checking live data i did notice sensor 2 readings had changed almost copying sensor 1, where i would have expected to see an almost stable .450 but no codes relating to this. The above missfire codes where rectified by fitting a new coil pack

Re: Citroen C3 1.0 2003 - CAT aging fault, code P0420 #

Posted by Steve Lacey <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5537' width='330' height='300' border=0 style='border:none;'> on July 24, 2011, 8:50 pm, in reply to "Re: Citroen C3 1.0 2003 - CAT aging fault, code P0420 #"
Stephen Lacey

Hi Alf, if front and rear lambda sensors are switching in unison then the cat is not working. The ecu checks for cat efficiency when fueling is in closed loop and car is cruising at approx 50 mph. Ecu monitors rear lambda sensor, if cat fails three times then MIL is illuminated. Driving round town may not illuminate MIL, however, dual carriageway or motorway driving will. Asta lavista, it will be back. By the way you cannot reset the ecu for this fault, you can only clear the fault code, which should clear as the conditions for monitoring are no longer being met. Regards, SteveL.

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