Citroen C5 hybrid stalling and fuel errors

I had something similar happen with my C5 – though it wasn't a hybrid. Check the cable and plug connections to the fuel composition sensor. It monitors the ethanol content in your fuel. If that sensor is giving a bad reading, it could explain the check engine light, stalling, and fuel composition error. Ethanol is alcohol. In modern gasoline engines its used to enhance octane and reduce emissions. Ethanol can be corrosive, that might explain the faulty plug connection. I would try to locate it and clean it.

Fuel composition sensor, eh? I hadn't considered that. Whereabouts is that located? Is it something easily accessible, or will I need to dismantle half the combustion chamber to get to it? Any chance you remember the exact error code you were getting? That might help me narrow things down.

On my car it was near the fuel rail, but being a hybrid, yours might be different. I recall it was difficult to reach. Honestly, if you're not comfortable poking around, I'd advise taking it to a workshop. Especially with a hybrid, you don't want to mess with the high-voltage components. They can read out the error code for sure. In my case the error was related to "Fuel trim malfunction".

Thanks a million! I took your advice and brought it to the shop. Turns out you nailed it – faulty cable and plug connection to the fuel composition sensor. 95€ later and it's running like a dream. Appreciate the help!