I keep getting a P0446 code on my truck and have been reding on the net and found this true. 04-06-0055) for code P0446 on 2000-03 Cadillac, Chevrolet and GMC full size utility trucks. </P>The charcoal canister stores gasoline vapors from the tank. When certain driving conditions are met, the computer supplies power to the purge and vent solenoids. The purge solenoid opens the vacuum line between the canister and the intake manifold and engine vacuum sucks the vapors out of the charcoal. The vent solenoid opens a fresh air line into the canister. If these vehicles are driven in dusty conditions, road grit and dust can accumulate in the vent solenoid resulting in a restriction. That will set a P0446 code. The fix is to replace the vent solenoid and bracket with a newer design. Remove the old vent valve bracket and install the new bracket (part #15105605) and a new vent valve (part # 15750484). Then, clear the trouble code. </DIV>if so it might be my problem because I am on dirt roads all of the time.