2004 silverado po446

[svtcobra03]

got a 2004 silverado with 138,xxx throwing a po446 code.

A code P0446 could mean one or more of the following has happened:

Faulty vent valve
Open, short or excessive resistance on Vent valve control circuit
Blockage of vent valve
Bad PCM

was wondering where should i start with this problem?
tia

[DC COBRA]

Just buy the new vent assembly. mounts back by the gas tank. The new one has a new routing for the vent hose also suppose to fix the problem.

DON

[ramairracer]

not so fast you have to make sure the fuel tank pressure sensor is reading correctly it can be reading full vaccum or full pressure. if its reading then its usually a canister and vent gclogged with dirt