Peugeot 607 Stalling Idling Poor Start

Sounds like a camshaft sensor issue to me. When those go bad, it messes with the ignition timing and can cause misfires, similar to a dodgy crankshaft sensor. Has it been running rough?

Rough, yes. Like it’s struggling to breathe sometimes. If it is the camshaft sensor, is there a way to be absolutely sure before I start replacing parts? I don’t want to end up chasing ghosts.

The symptoms definitely point to the camshaft encoder wheel being defective. You could try checking the sensor itself, but honestly, it's tricky without proper diagnostic tools. Given the stalling and check engine light, I'd say it's time for a workshop visit.

Thanks. Workshop it is then. Turns out it was indeed the camshaft sensor – encoder wheel was the culprit as you suspected. Cost me 695€ to get it sorted. Appreciate the advice!