Getting P0455 DTC code
 

I have a 2004 Porsche Boxter. Recently the Check Engine Light has started coming on, usually soon after I have refuelled. I have a generic code reader, and it shows P0455. I can clear it, and it usually doesn't come back on until I refuel again.
Any ideas on what is wrong?

Bad gas cap or disconnected hose on EVAP unit. Usually the gas cap, which is also the cheapest and easiest to replace............

Would that not show a P0457?

From Porsche's OBD II manual"

"P0455: Fuel tank pressure below lower limit

Possbile cause: Loose, missing or defective gas cap
Vent lines disconnected from EVAP canister......."

I could go on, but I think you get the picture........................