Peugeot 308 Throttle Valve Issue

Sounds familiar! I've got a 308 diesel too, and I had almost the exact same symptoms a while back. Started with the fuel efficiency dropping, then it became a real pain to get the engine going. Did you notice anything weird with the throttle response itself?

Throttle response seems normal to me. What was the problem with yours exactly?

Turned out it was the accelerator pedal module causing the issue. Apparently, it can mess with the throttle valve readings. The garage told me it's a common thing. I'd get it checked out professionally if I were you.

Thanks for the heads-up! I took it to a local garage, and you were spot on – defective accelerator pedal module! Cost me around 205€ to fix. Appreciate the help!