S90 Diesel Stalling and Rough Idle

I had similar symptoms in my S90. Does the engine completely die, or just stumble? It might be worth checking the fuel pump relay and connections. A faulty relay can cause intermittent fuel delivery issues leading to stalling and starting problems.

Thanks for the quick reply! When you say 'connections', are you referring to the wiring harness that connects to the fuel pump itself? And did the check engine light come on for you as well?

Yes, I am referring to the wiring harness and plug connection. Corrosion or a loose connection can definitely cause those symptoms, and trigger the check engine light. I would advise against further diagnosis without professional tools, and instead suggest taking your S90 to a trusted workshop.

Thanks for the help! I checked the fuel pump connections as suggested, and it looks like you were right. The cable was defective, causing a bad connection. I took it to a shop, they replaced the connection, and the error is gone. Total cost was 95€ Appreciate the pointer!