Megane starting stalling camshaft sensor issue

Sounds like a plausible diagnosis. A failing camshaft sensor can definitely cause those symptoms. The ECU uses the camshaft and crankshaft sensor signals to determine ignition timing and fuel injection. When the camshaft sensor signal is erratic or missing, the ECU can't accurately determine the engine's position, leading to starting problems, stalling, and the check engine light. Have you checked for any error codes?

Yeah, I read the codes, and it's throwing a code related to the camshaft position sensor. Is it possible the encoder wheel on the camshaft itself is damaged, and not just the sensor?

Absolutely, a damaged encoder wheel could be the culprit instead of a faulty sensor. If the wheel has bent or missing teeth, the sensor will not be able to read the camshafts position correctly, and produce an erratic signal. Given the symptoms and the error code, you are facing a mechanical issue which requires a professional. I would recommend taking it to a workshop.

Thanks for the help! I took it to a workshop, and you were right. It wasn't just the sensor; the encoder wheel on the camshaft was damaged. Ended up costing me 695€ to replace it all, but at least it's running smoothly now.