P0442...Already tried the obvious..

[ARogg619]

Hey All,
I got a 2000 Yukon with the 5.3. Roughly 160k on the odometer. I have a SES light code P0442. Ive changed the gas cap and Vapor Canister Purge Valve on the intake which everyone says is most common. Inspection is up at the end of this month so im trying to get it worked out. Anything else im missing that should be obvious? Im trying to avoid a hefty mechanic bill since I just put a tranny in my dads truck and that wiped me out ( over $4k ).
TIA

 

[OR VietVet]

An inexpensive attempt would be to disconnect the evap lines and blow them out. Many threads here about that and your concerns.

 

[Fless]

The canister vent valve should be open when the truck is off and, when the truck is running, it's commanded open and closed as needed. You can attempt to blow through it in place to test, or remove it to test for an intermittent fault. Applying 12v DC to the terminals should close it; polarity doesn't matter. Cycle it on and off while blowing through it to make sure it's working properly; I had an intermittent one that wouldn't always close completely.

A 'purge and seal' test would help diagnose without spending money on it. All you need is a capable scanner for that.

 

[Scottydoggs]

evap leaks can be a real pita. best bet is to smoke test it and look for the leak. and having a tech 2 or other scanner that can control solenoids, they can be commanded open and closed the smoke will come through the solenoid when open, and not when closed if working.

or if you got a tuner near by you can have all the evap codes deleted and never worry about that damn issue again. aka exactly what i did. being i own a hptuners made that decision easy. i did try to fix it tho. failed at every turn, so its gone now for like 4 years now. pass nj state inspection every time.