DTC P0446 - Evaporative Emmission Control System Vent Control Circuit
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 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
Hope helps (remember to rate this answer).