when my AMM went bad - for my American market car my CHECK ENGINE LIGHT came. However the AMM went bad first and the CEL didn't come on until about a 100 miles latter.

My AMM symptoms were most noticeable during rapid acceleration, I was getting very jerkt transmission shifts.

Since the AMM's seem to have a finite life it is worth changing out, yeah some techs say don't replace anything that's not broken, But this is your own car and you don't have to explain things to a customer.

There were some posts explaining in detail how to read OBDII codes that indicate a bad AMM and verify in fact that the AMM is the culprit, And some people have had the AMM codes activated without going through the diagnostic procedure to verify a bad AMM and when they changed out the AMM that didn't fix the problem - though that is rare compared to bad AMM's simply dictated by the OBD II codes only and fixed with a new AMM.

So when yoy get a new AMM use a good trusted source like FASTLANE or a local dealership and be leary of e-bay, because a used bad AMM taken out of a problem car can be easily cleaned to look brand new