1999-2007 Chevrolet/GMC DTC P0446 Set, Check Engine Light On

Subject: DTC P0446 (Restricted/Blocked EVAP Vent Path) Set, Check Engine Light On (Replace Evaporative Emission (EVAP) Vent Valve Solenoid Assembly and Add/Relocate Filter Box Using Service Kit)

Models: 1999-2007 Chevrolet Silverado (Classic) Models, 1999-2007 GMC Sierra (Classic) Models, 2007-2008 Chevrolet Silverado Models, 2007-2008 GMC Sierra Models


Some customers whose vehicles are operated in dusty type environments, such as farming or mining off-road type applications, may comment about the illumination of the check engine light, with a DTC of P0446 (Restricted/Blocked EVAP Vent Path) being set.


Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.

Correction (1999-2007 Classic/Old Style Models)

After following the published SI diagnostics for P0446 and determining that the EVAP canister vent valve is the cause of the MIL light, replace the existing EVAP canister vent valve assembly with a new assembly. This new assembly is a sealed unit that is designed to be vented through a remote filter box. To ensure correct installation, follow the procedures below.

1999-2003 Model Year (Use Service Kit P/N 19152345)

1. Raise the vehicle. Suitably support the vehicle.

2. Disconnect the EVAP canister vent valve electrical connector, if equipped.

3. Disengage the two vent valve pipe clips securing the pipe to the underbody. ... Download File PDF

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