I have a 98 V6 Camaro and I have a PO442 code that is driving me crazy. I bought a new gas cap and checked all the vacuum lines that I know of. I did notice that on the evap line that reads "caution fuel vapors" that I see a service port that has a green cap. Sounds crazy but it looks like someone burnt it somehow almost in half. I checked it out with carb cleaner when the engine was cold and there was no idle change. Is that suppose to be a shrader valve of some sort or just a dust cap for the service port? If there is a pin hole in that cap, would that cause the code to show up? Another question is when I replaced the gas cap how long does it take for it to clear if that was the problem. It wasn't cleared at the parts store after I put it on.

 

I work at an auto parts store and see this code a lot. It could be the EVAP cannister purge/vent valve solenoids or the cannister itself. These things saturate over time and need to be replaced. I hate trying to diagnose the 442 code but I hope this helps. Best of luck. Also, you could disconnect your battery for five minutes and clear the code or drive about 40 miles to see if it clears.