S90 Diesel Fuel Consumption and Starting Issues

I had similar symptoms with my Opel Insignia, but it was the petrol version. Higher fuel consumption and poor starting were my main issues. Have you checked the throttle position sensor readings?

Thanks. What specific throttle position sensor values or ranges should I look for to confirm a problem?

My readings were all over the place. I couldn't fix it myself and took it to a workshop. They said the throttle body was faulty. Maybe get yours checked out professionally.

I had a mechanic inspect it and they confirmed a defective throttle valve and a faulty accelerator pedal module. The repair was 205€, including parts and labor. Thanks again.