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P0446 GMC

P0446 GMC - Evaporative Emission Vent System Performance

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Possible causes
- Plugged vapor canister
- Faulty vent solenoid
- Pinched or blocked EVAP hose
- Faulty FTP sensor
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Tech notes
Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.

There is a bulletin for the following models:
1999-2007 GMC Sierra (Classic) Models
2007-2008 GMC Sierra Models
GMC Factory Service Bulletin OBDII Code P0446
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When is the code detected?
The Powertrain Control Module (PCM) sets the P0446 code if the vacuum decay rate is greater than a predetermined value.
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Possible a noticeable fuel odor caused by the release of fuel vapors
P0446 GMC Description
The Powertrain Control Module (PCM) monitors the performance of the Evaporative Emission (EVAP) system by applying a predetermined level of vacuum to the EVAP system then monitors the vacuum decay rate.
GMC Technical Service Bulletins for P0446 code
2003 GMC SIERRA CLASSIC ENGINE AND ENGINE COOLING:ENGINE Details
2003 GMC SIERRA CLASSIC ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL Details
2003 GMC SIERRA CLASSIC FUEL SYSTEM, GASOLINE:STORAGE:TANK ASSEMBLY:FILLER PIPE AND CAP Details
2004 GMC SIERRA CLASSIC ENGINE AND ENGINE COOLING:ENGINE Details
2004 GMC SIERRA CLASSIC ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL Details
2004 GMC SIERRA CLASSIC FUEL SYSTEM, GASOLINE:STORAGE:TANK ASSEMBLY:FILLER PIPE AND CAP Details
2005 GMC SIERRA CLASSIC ENGINE AND ENGINE COOLING:ENGINE Details
2005 GMC SIERRA CLASSIC ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL Details
2005 GMC SIERRA CLASSIC FUEL SYSTEM, GASOLINE:STORAGE:TANK ASSEMBLY:FILLER PIPE AND CAP Details
2006 GMC SIERRA CLASSIC ENGINE AND ENGINE COOLING:ENGINE Details
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