Avantime poor starting and high fuel consumption

Sounds familiar. I had a similar problem with my old Volvo V70. Higher fuel consumption and poor starting were the main symptoms. Have you checked the throttle position sensor? It might be sending incorrect data to the ECU, messing with the fuel-air mixture. Does the engine idle smoothly, or is it erratic?

The engine idle is somewhat erratic, yes. Could you elaborate on your experience with the throttle position sensor? Did replacing it resolve the issue in your Volvo?

Yep, replacing the throttle position sensor fixed it for me. But given your erratic idle, I'd say get it checked by a workshop first. Could be the throttle body itself needs cleaning or replacement, or even the accelerator pedal module as you suspected. A diagnostic scan should pinpoint the exact cause.

I took it to the workshop, and indeed, the accelerator pedal module was defective, as I initially suspected. The replacement cost was 205€. Now the car runs smoothly and fuel consumption is back to normal. Thanks again!