Hello all

I had this saxo in yesterday, customer complained of surging when driving along,road tested vehicle and it does surge sometimes.

Had a visual look under bonnet for anything obvious, vehicle has full service history low milage car.

Plugged in scan tool came up with the following fault codes -
P0420 ageing cat

P0172 Adaptations,system too rich

P0134 o2 upstream o2 sensor

I scoped the pre a post o2 sensor and the were a mirror image of each other, which means the cat is u/s.Fitted new one and that was ok.

I then went into obd to look at fuel trims and found short fuel trim at around +10,there is no air leaks, removed throttle body and cleaned housing, refitted all ok, stft down to +2.long term fuel trim still at +4.7.

I tried clearing fault code in eobd and manufacturers side and the long term fuel trim is stuck at +4.7? does any one know if this is correct?

Thanks for any advice