Volvo 480 Club Europe

Thanks everyone i have now found the fault, it was as AleksanderHugo suggested, i have a faulty o2 sensor signal wire, the sheilding has broken down and is a constant short to earth, cut the sheild earth wire and it now runs as should. Will at somepoint run a new sheilded wire. Thanks for all the he...

Thanks for that, i will give it a try if i can find another loom with the wire in

Tried BOSCH and NGK o2 sensors, cat is a good make, not cheap one.
It seams to me with the scope readings that the o2 sensor is not getting hot enough and so not sending a high enough voltage to the ECU, no flash codes present in system

Engine oil and filter will not cause 9% co2, its replaced every year, airfilter too, fuel filter is new also.

High, this is my first ever post, My 1995 480 celebration will not pass MOT emissions due to high co2, i have tested and replaced everything, air intake temp sender, coolant temp sender, map sensor, plugs, coil pack, and o2 sensor, even tried a new ecu and cat. I haven't found an air leak to the inl...