r/subaru • u/No-Delivery8757 • 6h ago

P0455 Code (EVAP System)

2022 Impreza Hatchback, has check engine light popped up 2 days after filling the tank. Code is P0455

~48000km, Car drives very normally as usually. Without clearing the code myself, I tightened the gas cap and drive for more than 100km, check engine light still there.

Gas cap looks very normal to me (or I just dont know how to inspect?), had a shop put on another gas cap from another impreza, they said check engine light still popped up,

I am very new to car and what should I do/inspect/diagnose next? Would this be something still under warranty- checked warranty booklet, very less likely.

What would it possibly be other than gas cap?

Thanks everyone in advance.

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u/Chippy569 Senior Master Tech 4h ago

P0455 just means large evap leak detected. The gas cap not being installed correctly is far and away the most likely suspect, but a hole anywhere in the system (where the diameter is 1mm or more) will need to a P0455.

If you're damn sure it's not the gas cap, next step is smoke testing, which probably means take it to a shop for diagnosis.