C30 Terminal 30 Error Poor Starting

I had something similar happen with my C30 – though I didn't get that specific error message. The poor starting sounds like the battery might be heavily discharged or even defective. Have you checked the voltage? I'd also look for any parasitic draws that might be draining the battery when the car is off. Electrical faults can be a nightmare on these cars!

Thanks! How did you track down the parasitic draw? I have no idea how to find one.

Well, in my case, I initially suspected a faulty aftermarket alarm system, as I'd experienced issues with those before on other vehicles. But it ended up being a short in the fuse box, causing a small but constant drain. I'd suggest getting it checked by a workshop if you're not comfortable with electrical testing. Don't want to cause more damage. Best of luck, this may require professional intervention. I recall paying around 290€ for a similar repair back then

Thanks a lot for the advice. I will take it to a shop to get it checked properly. Sounds like it could be more involved than I initially thought!