Volvo S40 diesel engine stalls at idle

Sounds familiar. I had a similar experience with my old Renault Megane diesel. Check engine light, stalling, and power loss – all point to fuel delivery issues. In my case, it ended up being a faulty fuel pressure sensor. It wasn't the pump itself, but it was throwing off the fuel mixture. Have you checked the sensor readings?

Thanks for the quick reply. I appreciate the Renault insight! When you mention the sensor readings, do you mean using an OBD reader to monitor the live data stream from the fuel pressure sensor? Or is there another method you'd recommend? I'm trying to get a better handle on this before potentially replacing the high-pressure pump.

Yes, I mean using an OBD reader to monitor the fuel pressure sensor's live data. See if the readings are erratic or out of the specified range. While my issue was 'just' the sensor, those symptoms definitely suggest a deeper fuel system problem. Honestly, given the potential complexity and high pressures involved, I'd strongly advise getting it checked by a workshop with experience in diesel fuel injection systems. Could save you a lot of time and potential damage.

Thanks, that's solid advice. I appreciate you sharing your experience with the Renault. I've taken your advice and had it checked by a workshop. Turns out my initial diagnosis was correct: fuel volume regulator was indeed defective, caused by a failing high pressure pump. Repair cost me 1510€, but at least it's running smoothly again.