207 1.4 Petrol Antipollution Fault

[CitroJim]

This is on the Ex-SWMBO's 207. 1.4 petrol (ET3) with Magnetti Marelli MM6LP Injection.

On and off for months now she's been getting the Engine Management Light and the dread "Anti pollution" message up in the display, especially in very cold weather.

I ran the PP2000 across it today and two faults are flagged up. A Permanent one to do with Mixture Coherence and the other to do with an intermittent short to +ve on the upstream O2 sensor. Both faults clear but reappear as soon as the engine is restarted.

On looking at live data the upstream O2 sensor signal looks OK most of the time but occasionally goes static at 800mV but the downstream one started off a 3800mV and then went resolutely static at 800mV.

To me the downstream one looks dodgy but PP2000 moans about the upstream one.

Internet searches seem to suggest one or both of these sensors may be the culprit. Are they both the same?

I also noted a routine on the PP2000 to reset the ECU auto adaptives Internet searches on this suggest this procedure needs to be carried out when replacing the oxygen sensors or the faults won't stay cleared but it's not explained what it does. Can anyone explain and can anyone please confirm a duff O2 sensor or two is a reasonable diagnosis?

Or else, what else might cause this fault. SWMBO says the car runs OK albeit a bit thirstily...

I had to laugh at Robyn (who's home from Uni this weekend) when I told her mum she may have a duff oxygen sensor. Robyn sagely nodded her head and said "Thought so. That's what was wrong with my car mum, I know all about those.."

[mlkey]

Sounds like the same problem as I am having here http://www.frenchcarforum.co.uk/forum/v ... =4&t=38053" onclick="window.open(this.href);return false;.

I replaced the upstream sensor which did not fix it and will be checking the wiring on the heater circuit when the weather warms up. I have heard that the only fix is an ECU update, but it worked before so what has changed.. Perhaps we can work together on this one to try and fix it?

[wheeler]

Auto adaptive is when the ECU 'learns' your driving style, When you reset the auto adaptives it clears & resets the part of the memory that learns your driving style. It should be done when replacing most sensors & auctuators.
How is the upstream sensor behaving ? when the engine is warm and in open loop the voltage should constantly fluctuate between 100-800mV @ idle.
As far as the downstream one goes the actual reading is not too important as long as it stays fairly static once the engine has warmed up.
I dont believe there is any difference in the actual sensors but the connectors are usually different so they cant be interchanged by mistake & they may have different wire lengths.

[Deanxm]

So long as the sensrs are the same type it is fine to swap them, my friend has an 07 Porche Boxster s and he fitted a pair of downstream O2 sensors from a volvo and a rover by soldering them into the existing Porche lead lengths as his was accident damaged and he had no problems at all, i soldered in a saab one onto a rover i had that had oil contaminated its O2 sensors and that was fine too.

Both could have failed its true but unless the exhaust is contaminated heavily i doubt it very much, if you have checked for a short in the upstram sensor and come up blank i would get another new looking upsteam from the breakers and solder that in to save money and test, if that fails i would be looking for the usual mixture upseting candidates in the injection system, seems odd to me the ecu throws a wobbler in cold weather and the engine is running rich.........................

D