lambda sensor problems

[s40madness]

Bascially the lambda light came on a few weeks back, checked codes and it was rear o2 sensor so i replaced it, all was well until a week on the lambda light has come on again, i am a bit stumped.. Does anybody have any ideas what might cause this?

[960kg]

Originally Posted by s40madness

Bascially the lambda light came on a few weeks back, checked codes and it was rear o2 sensor so i replaced it, all was well until a week on the lambda light has come on again, i am a bit stumped.. Does anybody have any ideas what might cause this?

What was the error code number?

Now the light is on again check the error code again and see if different?

People always say the rear sensor only determines the state of the cat. but this is only one of it`s job`s.

For the rear sensor to be able to do the cat. job properly the front sensor has to be in good condition as well as they swop signals to determine if all is ok, if not the emission light will be on.

Also the communication between these two sensors does determine fuel trims and if the ECU does not agree the emission light is on again. It sorts out the gases going in and the gases going out the cat.

If you have the same error code again for the rear check the plug connection first to see if ok.

I hope you didn`t touch the filament on the end of the sensor as they have to be treated the same as headlamp bulbs otherwise the fingerprints burn into the surface and give wrong readings.

Last of all was it new or 2nd hand or a cheap Rear O2 sensor and from where??

[s40madness]

Same code, i got my dad to take it to work with him, he is a volvo technician, so hooefully he hasnt fitted it wrong.. That would be awkward for him lol it was an ngk one because volvo wanted 130 quid for it and that was even at cost plus 10%