C5 Diesel Rough Running

Interesting. I had very similar symptoms on my C5. Rough idling, check engine light... sounds familiar. Do you experience any fuel economy drop? Have you checked the airflow sensors? What diagnostic tool are you using? Is it able to perform an actual system reset and compensation adjustment?

Yeah, fuel economy has definitely taken a hit, I'd say about 10-15%. I haven't checked the airflow sensors specifically, but I did give them a quick visual inspection. As for the diagnostic tool, it's just a generic OBD2 scanner with basic reset functions. It clears the error, but it comes back after a few kilometers. Do you think a proper compensation adjustment might sort it, or is it more likely an injector issue like I suspect?

Given the fuel economy drop and recurring error, it does indeed point towards an injector problem, particularly since the error code relates to compensation. While a forced compensation adjustment might temporarily alleviate the issue, the underlying problem will likely persist. Based on my experience, and given that the error returns so quickly, it is a defective injection valve. I would recommend visiting a workshop that can perform in-depth diagnostics and injector testing, they have the proper equipment.

Thanks for the input! I was hoping it wouldn't be the injectors, but it sounds like that's the most likely culprit. Dropped it off at the mechanic today, they confirmed it was a faulty injector and quoted me 515€ for the repair. Ouch! But at least it should solve the rough running and get rid of that annoying light. Cheers!