C8 check engine light rough running

Rough running and a check engine light on a diesel C8? Sounds like the water sensor is the culprit. Before diving into testing the sensor, I would inspect the connector and wiring. Diesel engines are like fussy toddlers when it comes to electrical connections - a loose or corroded connection can throw everything off. Have you checked the connector and wiring harness for any obvious damage?

Thanks for the tip! I had a quick look at the connector, but maybe I didn't go deep enough. How exactly would you test the wiring for issues? Is there a specific tool or method you'd recommend? I am not sure how to test a cable.

Think of the wiring like a garden hose. If it's kinked (damaged), the water (electricity) can't flow properly. A multimeter is your friend here. Check for continuity. If you are not comfortable with a multimeter, it might be best to take it to a workshop. These electrical gremlins can be a real pain to track down without the right tools and knowledge.

You were spot on! I took it to the shop, and it turned out to be a dodgy connection on the water sensor. They cleaned it up and secured it properly. Cost me 95€ and the engine is now running smoothly. Thanks for pointing me in the right direction!