Prius engine stalls when idling

Sounds familiar. I had similar symptoms in my old Renault Megane. The check engine light kept popping up, and the engine would occasionally stall. I would suggest checking the EVAP system. Did you check the hoses for cracks as well?

Thanks, I checked the hoses quickly for cracks, but not thoroughly. Were your hoses clogged as well? What fixed it for you? Trying to avoid the mechanic if I can.

My hoses weren't clogged, but they were leaking from tiny cracks. The mechanic found it fast. I'd suggest a workshop; they have the right tools to diagnose it properly. It could save you money.

Thanks! Took it to a mechanic, and you were right – it was the tank ventilation valve. The hoses were clogged and damaged. The repair was about 175€, but the check engine light is gone, and it's no longer stalling. Appreciate your help!