P0446 Evaporative Emission Control System Vent Control Circuit
OBD-II Trouble Code Technical Description
Evaporative Emission Control System Vent Control Circuit Malfunction
What does that mean?
This diagnostic trouble code (DTC) is a generic OBD-II powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may vary depending on the model.
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 12V battery 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.
There will be no obvious symptoms to driver, other than Malfunction Indicator Lamp (MIL) illumination.
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
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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