Jonathan Morgan
I hooked it up to the gas analyser, engine at 90C & at fast idle it had a CO of 1.5%.
While still connected to the gas analyser I cleared the DTC & watched the CO drop almost intaneously down to 0.02%, this is a regular occurence with VAG software.
The ECU likes everything tickety boo or it defaults into a strange rich mixture mode.
I also had the runaround as you are describing above, with a Bosch O2 sensor on a 2.0 Golf.
I fitted a new Bosch sensor, after which every couple of weeks it would return with the MIL on & a fuel trim fault logged.
After much testing & getting nowhere, I binned the Bosch sensor & replaced it for a genuine VAG (Bosch) sensor - it has been back for servicing etc since with no repeat of the fuel trim fault.
We now only fit genuine sensors across the board, we've been legged up to often with AMM's, coolant temp senders, O2 etc....
hth,
Jon.
on March 21, 2011, 8:13 pm, in reply to "