C30 fuel consumption starting issue

I drive a C30 too and had similar issues. Have you checked the throttle position sensor? A faulty sensor can mess with air intake readings, affecting fuel efficiency and starting.

Thanks. Can you explain how to check the throttle position sensor? Did you see any error codes when you had this problem?

I didn't check it myself. I took it to a workshop. They found it fast with diagnostic tools. It's best to get it checked professionally before replacing parts.

Thanks for the advice. I took it to a service center, and the throttle valve was defective. The accelerator pedal module was the cause. The repair was about 205€, including parts and labor. It's running great now, and fuel efficiency is back to normal.