2006 Chevrolet Tahoe • V8 4WD Automatic • 96,000 miles

Code on my 2006 tahoe shows up # is po446 it saids it is EVAP Emission control system vent circuit malf was wonering if sensor needs change or what
December 4, 2010.

P0446 Evaporative Emmission Control System Vent Control Circuit
OBD-II Trouble Code Technical DescriptionEvaporative Emission Control System Vent Control Circuit Malfunction

What does that mean?Evap vent valve has only one purpose. It closes in order to seal the vent so the EVAP system can pressurize and ensure there are no leaks. Evap vent valve is usually supplied Batt. Voltage with key on. The ECM's driver controls the ground, and when grounded, activates the valve (closing it). If the ECM detects a short to ground, and open, or a short to battery voltage on the control circuit, P0446 will set. Code also may refer to ECM detecting that EVAP system is unable to achieve or maintain vacuum during test.

SymptomsThere will be no obvious symptoms to driver, other than MIL illumination.

CausesA 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
Possible SolutionsWith a P0446 OBD-II trouble code, here are some things to try: Replace Vent valve
Repair open, short, or resistance problem in control circuit
Repair open, or short, or resistance problem in power circuit
Replace PCM

Dec 4, 2010.
THANKS rasmataz, you are great for explaining and what to check

Dec 4, 2010.