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1999 silverado has code p0446
1999 Chevrolet Silverado 1500

1999 Silverado has code p0446

(1999 Chevrolet Silverado 1500)
replaced the evapo vent solenoid and purge valve. code still comes back
1 answer & 0 comments
Popular Answer
on November 17, 2015
that code didn't mean to replace those two things that you replaced.the code is a STARTING point to CHECK/TEST possible things that could be wrong with the evap system,could be as simple as an evap hose not holding vacuum.......................................
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. Symptoms There will be no obvious symptoms to driver, other than Malfunction Indicator Lamp (MIL) illumination. Causes 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 Possible Solutions With 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
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General Diagnosis
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on November 17, 2015
that code didn't mean to replace those two things that you replaced.the code is a STARTING point to CHECK/TEST possible things that could be wrong with the evap system,could be as simple as an evap hose not holding vacuum.......................................
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. Symptoms There will be no obvious symptoms to driver, other than Malfunction Indicator Lamp (MIL) illumination. Causes 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 Possible Solutions With 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
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