| Re: 99 Catera Error Code P0455 Make sure the gas cap is tight (several clicks) and wait for several start / drive / warm up cycles to clear the code itself. It may take a few days - the CEL has to see the condition cleared three times in a row or something like that. If your reader can clear the code, you can try that and see if it comes back. If it doesn't clear itself, I'd try a new gas cap.
BTW, I think it is good for your car to keep the fuel level filled, this protects the gas pump, etc. I have my Catera for 11 1/2 years, always used premium.
Barry |