C5 Oil Pressure Warning Light

I had similar problems with my C5. The oil light came on. Have you checked the oil level? What does the oil look like? Maybe it's contaminated with fuel or coolant.

I checked the oil level, and it seems fine. But how can I tell if the oil is contaminated? Is there a way to check it myself, or should I just go to a mechanic?

In my case, the oil had a milky look because of coolant contamination. But better safe than sorry, especially with diesels. Take it to a workshop before you cause serious engine damage.

I took it to the workshop, and they said the oil was badly contaminated because I missed the service. It cost me 165€ for an oil change and new filter, but at least it's sorted now. Thanks a lot for the advice!