Serena cold start issue

Sounds familiar. My old 2008 Renault Scenic had similar symptoms – rough cold starts and terrible fuel consumption. Didn't get any error codes, though. Have you checked the heater wiring? Could be a simple connection issue.

Yeah, I checked the wiring harness, but it looks okay. Did your Scenic have a similar electric auxiliary heater? Did replacing it fix the problem?

Yep, mine had one. Replacing it fixed the cold start and fuel consumption issues right away. With your symptoms and the error code, I'd suggest getting it checked out at a workshop. Probably the heater.

Thanks, I replaced the electric auxiliary heater, and that fixed it! Starts smooth now, and fuel consumption is back to normal. Cost me about 350€. Appreciate the help!