I got the error code P0455. I check the gas cap but the engine light still on. The car still under warranty for emmision and powerdrive not bumber to bumper. The milage is 43,450 I bought it at 41,000k. The panel for the plug was missing so the dealer must have run the diag. Mazda wants to charge me $100 for Diag check. I am under warranty? And can I safely reset the engine light with my OBD II tool? Thank you.