S80 Diesel starting stalling issues

Sounds like it could be the fuel pump, especially with those symptoms. Hard starts, stalling, rough running, and increased fuel consumption are all classic signs. Have you checked the fuel pump relay or any of the wiring connections to the pump? A faulty connection could cause similar issues.

Where exactly is the fuel pump relay located? And what kind of wiring issues should I be looking for specifically?

The relay location can vary, check your manual! As for wiring, look for anything obvious – corroded connectors, loose wires, or damaged insulation. It's a common weak point. But with all those symptoms, and the error code, it really does point to the fuel pump itself. You might be best off getting it checked by a workshop to be sure.

Thanks for the advice! I checked the wiring as best I could, but didn't find anything obvious. Took it to a workshop, and you were right, it was a bad connection to the fuel pump. They fixed the cable and the plug connection. Cost me 95€, but at least it's running smoothly now.