Hey everyone, first time posting here. I have an '09 Silverado Z71, 5.3 with 60k mileage, CEL on and keep getting the0442 code. I've already replaced the vent valve and filter box and the truck already had the relocated kit installed. I've had no issues with the gas cap & never got the tighten gas cap message on the DIC. Trying to fix without taking to the shop ' cause I need new tires (close to $1,000). Any ideas? I was thinking of replacing the tube between the vent valve & filter box since it is spliced to the new valve with 5/8 heater hose (as directed by the service bulletin I found). Also wondering if the purge valve may be the cause. I have a code scanner & the code returns within a few days of erasing.

I also have a 2007 Monte Carlo that just started pumping out the same code. Only thing I tried with it was a new gas cap, code still returns.

 

at this point you will need to have the evap system smoke tested to locate the small leak.

 

How much $ should I expect to pay to have it diagnosed with the smoke test? Does the tank need to be lowered to do this? I hesitate because last time I paid for a vehicle to be serviced at a dealership, they charged me over $300 and gave me the wrong diagnosis. If the diagnosis costs about the same as throwing parts at the vehicle, I'll just change the parts.

 

for any diagnosis authorize 1 hour (the hourly door rate should be posted) and no more. If they can't find it in that time, they are incompetent. So be prepared to pay for the one hour diagnostic, the part, and labour to install the part. Your probably looking at $300 again.

If you choose to return to the same dealership; insist on a different technican and tell them why. There are all different skill levels at any shop; ask for the best tech.

there is a long list of possible faulty parts: filler neck, gas cap, Fuel tank pressure sensor, purge valve, vent line.

 

Thanks. I'm gonna replace the purge valve & vapor cannister tube as well as visually inspect the other lines & fuel pressure sensor before I take it in. The parts are cheap online so it's worth a gamble.

 

good luck.

fyi...the evap monitor withholds the test if the fuel level is less than 1/4 tank or MT 3/4 tank.