G Klasse Check Engine Light Air Valve Issue

Sounds familiar. I have a G Klasse too, though I haven't seen that specific error code. If it's the air valve, definitely check all your vacuum hoses. A vacuum leak can cause all sorts of weird problems with the air intake. It's like a domino effect, messing with everything from the air-fuel mixture to the manifold pressure readings. Are you hearing any hissing sounds that might indicate a leak?

No hissing that I can hear, but those vacuum hoses are a pain to get to. Was your issue also the hose connection from the pump to the valve, or somewhere else in the air supply system?

I didn't dig that deep myself to be honest. I brought it to a workshop. Based on your description, it sounds like the hose connection from the pump to the valve is a strong possibility. But without proper tools, it's hard to pinpoint. If you're not comfortable tracing all those vacuum hoses and testing for a vacuum leak, I'd suggest getting it checked out by a professional. Could save you a lot of headache in the long run.

Thanks for the advice! Turns out it was exactly as I suspected: the hose connection. Got it sorted for 175€. Appreciate the help!