C5 Cold Start Rough Running

Sounds like a potential fuel delivery issue alright. The symptoms you're describing definitely point towards a possible injector problem. Has the car been sitting for extended periods or do you use fuel additives? Sometimes a good injector cleaner can help, but if it's a persistent problem, it might be a defective injector.

Thanks for the quick reply! It's not been sitting unused for long periods, and I haven't been using any fuel additives recently. Would a simple injector cleaning actually do the trick, or am I just delaying the inevitable here? I'm not afraid to get my hands dirty, but I also don't want to waste time chasing ghosts if the injector is just plain knackered.

While injector cleaner can sometimes help with minor blockages, a defective injector is a different beast. It's like trying to fix a leaky faucet with a band-aid – it might temporarily slow the drip, but it won't solve the underlying problem. Given the poor starting and rough running specifically during cold starts, and considering the mileage, it's highly probable the injector is faulty. At this point, I'd strongly advise getting it checked out by a workshop with proper diagnostic tools.

Thanks for the advice. I suspected as much, but it's good to get a second opinion. Looks like a trip to the shop is in order. Just got the bill from the mechanic: a new injector and labor came out to 515€. Ouch! But at least the car starts like a champ now. Lesson learned!