Peugeot 308 Hybrid automatic transmission issue

Sounds like a headache. Have you checked the vehicle's voltage? Undervoltage can cause weird issues with modern automatic gearboxes. When was the last time you had the battery checked or replaced?

Thanks for the tip! I hadn't considered the voltage. How would low voltage impact the transmission? Is there anything I can check myself before taking it to a mechanic?

Low voltage messes with the solenoids and sensors that control the transmission's shifting. They rely on a stable voltage to operate correctly, causing erratic behavior and error codes. You can check the battery voltage with a multimeter; it should be around 12.6V when the engine is off. But honestly, with those symptoms, you're probably best off getting it properly diagnosed at a workshop.

You were spot on! I took it to a local workshop, and undervoltage was indeed the cause. They found worn-out transmission oil due to the electrical issue. The total repair cost was around 240€. Thanks a bunch for pointing me in the right direction!