C4 start stop problem

Hey! I had a similar experience with my C4. Start-stop acting up and throwing errors can often point to a weak or failing battery, especially with a diesel. Diesels need a lot of juice to crank over, and the start-stop puts extra strain on the battery. When you say 'shuts off unexpectedly', do you mean instead of automatically restarting, or does it just die at random?

Thanks for the reply! To clarify, the engine shuts off at a stop as it should, but then it doesn't automatically restart. I then need to manually start the engine, which is a pain.

Ah, okay, that sounds very similar to what I experienced. Think of your car battery as a bucket holding water. The start-stop is constantly dipping into that bucket, and eventually, if the bucket isn't refilling fast enough or the battery is old/damaged, it runs dry. In my case, it turned out the battery was heavily discharged and probably defective. I recommend taking it to a workshop to get the battery properly tested. Cost me about 290€ to replace.

Thanks, that's really helpful! I'll take it to a workshop to get the battery checked. I really appreciate your help!