However, let's assume that it is a "true" reading (or at least in the right direction). That suggests a (very) rich mixture in that bank. Would a rich mixture damage the cats over time?
My understanding is that excessive heat (unburnt fuel) will damage the cats over a period of time.
I've only done about 1,500 miles in the last 12months. Is this relevant? And the battery went flat over winter - meaning loss of power to the ECU - so has something been "reset" somewhere that might cause this?
ECUs do learn, so a reset may have effected some aspects of the engine managment (fuel to air ratio); however, they generally adapy quite rapidly after a reset.
As a matter of interest, how far is the MOT centre from you house and did they MOT the car as soon as it arrive - or was it left to cool and then the MOT'd?
I have a car that reads high unless it has been given a good run and not allowed to cool down before the MOT.
