Yesterday the TÜV approval of my 850 and the trailer was available. The trailer got the badge without defects, the Volvo did not. In the car the AU was the problem: The measurement showed that the CO content is too high. 0.874% instead of maximum 0.3%. Error deleted and rereaded: A2 = 1-2-2 A2 = 5-2-1 B2 = 1-2-2 (can I ignore) At times the errors could not be deleted at all, sometimes they came again after the deletion, although the engine remained out Since I did not fall on the head bi My first thought: wrong air, lambada probe or cat. Unfortunately, the brake cleaner was all, so only one visual inspection was carried out – nothing found. The *Kat I replaced with a used part – MKL still glows. *Lambada probe replaced by used part, MKL still glows. *(Both parts are proven to be ok) Where is the dog hiding?