Hmm i duno.. here is the code

HISTORY DTC PO442
EVAP Emission
Control System
Leak (Small)
MIL REQUESTED
Since iGn NOT RUN
Since Clear FAIL
__________________

 

Wow!!.....no question...no vehicle info....what do you really expect here?

 

Yeah, vehicle information is a necessity.

I'm gonna guess it's a loose or failed gas cap.

 

sorry. i thought i included vehicle info in my signature. i have a 1997 blazer LT, 4 wheel drive. 160,000 miles. Ive had trouble with a service light before but its gone off after a few days. gas cap is only 2 years old. hmm, any more suggestions?

 

Could be any one of the many evap lines to the tank or between the tank and the charcoal canister. It could be one of the evap vent or purge valves, etc... I would first replace the gas cap again since it is by far the cheapest/easiest thing to do to start off with. From there, if it were my truck, I would hook up my computer and diagnose the EVAP system by monitoring the tank pressure, then opening and closing each of the valves to verify that they are working correctly. If that doesn't narrow it down, then most shops employ a smoke system to detect leaks.