I have a C270CDI with the P1189 code up, I was just going to post with my problem when I saw this thread. Where is the intake air control flap situated? The fault I have is intermittent loss of power. This car was run through a flood a few weeks ago which hydraulic'ed the engine. Rebuilt engine had done 1000 miles before problem started and this flap/valve must have been drenched with water but I cannot find it to check if it is rusted or gunged up? Customer has already replaced the AFS as Merc suggested most likely fault. A quick check of live data showed 0mg/h on AFM but to be honest I had little time to check if this was accurate or a software glitch. Going back tomorrow (Monday) to do a more thorough diagnosis. Andrew