S40 Engine Stalling

I had a similar issue with my S40, although I didn't check the error codes. The engine would stall at idle, especially when the engine was cold. Have you checked the air intake for contamination?

Contamination of the air intake, you say? Where exactly should I be looking, and what kind of contamination are we talking about?

Yeah, on mine the intake was heavily contaminated with gunk. I tried cleaning it myself, but ended up taking it to a workshop. They confirmed it was the IAC valve issue due to a dirty intake. It may be worth getting it checked by a professional.

Appreciate the advice! I took it to the shop as you suggested. Turns out you were spot on, intake was filthy and the IAC valve was shot. Cost me 425€ to repair. Thanks again for the help!