Hello, last week the Tüv was due. Well, bad luck – just failed at the AU. Unfortunately I was not there, the workshop master told me however, that the CO value was too high. He had also tried and the Volvo again warmed up on the road – but unfortunately did not succeed. The Volvo is a 850 T5 with automatic and LPG. Km-Stand: 380tkm. As layman I immediately remembered the Lambasonde and the Kat. Both are still the first ones. I tried the probe probably as first (if there were before I get a new cat for free, are there ways to test it with simple means? The exhaust gases smell/sink a bit strikingly – but it does squeak only as long as the outside temperature is low and the engine is cold. And what causes could a too high CO value still have? A month ago I first changed the exhaust/smoke damper. Because the previous owner had welded the connecting clamp, I had to What’s the problem with the flex? Can the lamda probe give the rest? I also suspected a leaky flex tube (woven tore), but the workshop meant a leak test would not have resulted in anything. I had recently checked the vacuum hoses, but also found nothing. Thanks and greeting, Martin PS. Normally I used the search function in detail, which in most cases also helps me. Unfortunately, it is not possible to search for “CO” and “AU”.