Citroen C4 high fuel consumption poor start

Greetings. The symptoms you describe certainly point towards a potential issue with the engine throttle, possibly a defect in the throttle valve or control valve within the air intake system. Have you inspected the throttle body for any visible signs of damage or excessive carbon buildup? Also, is the check engine light illuminated, and if so, have you retrieved any diagnostic trouble codes?

Thanks for the quick reply. I haven't checked the throttle body itself yet, but I have a code reader. I'll check for any error codes later today. I'll inspect the throttle body then too. Assuming it IS the accelerator pedal module, is replacement straightforward, or are there any hidden gotchas?

While a defective accelerator pedal module remains a plausible cause, I would nonetheless urge caution before assuming its definitive involvement. Considering the intricacies of modern engine management systems, and drawing upon related experiences, a precise diagnosis frequently mandates specialized diagnostic equipment to properly evaluate the functionality of the throttle valve and related components. I would strongly recommend seeking counsel from a qualified workshop to conduct a comprehensive examination. An eventual repair bill of 205€ is not unlikely.

Much appreciated for the advice! I ran the codes and got a throttle position sensor error, so I went to my mechanic as you suggested. Turns out the throttle valve was indeed defective! Got it replaced, and she's running like a dream now. Again, many thanks!