C30 engine stalling incorrect fuel composition

I have a C30 too, and I had a similar issue a while back. Same symptoms – check engine light and stalling. Did you check the connections to the fuel composition sensor? A bad connection can cause all sorts of weird readings.

Fuel composition sensor, eh? Where exactly is that located, and what should I be looking for? Is it obvious when the cable or plug is defective?

It's usually somewhere along the fuel line, near the fuel rail. Honestly, I couldn't tell you exactly where on the C30 without looking it up. When mine was doing that, the plug looked ok to me, but the mechanic said it was corroded inside. I'd suggest getting it checked out by a professional. Cost me about 95€ to fix, including the part and labor.

Thanks a lot for the info! I'll take a look at the fuel composition sensor and its connections. If I can't find anything obvious, I'll take it to my mechanic. At least now I have an idea of what to tell him. They replaced the defective cable for 95€ and the problem is now solved. Cheers!