Code Definition

P0446 — Evaporative Emission Control System Vent Control Circuit Malfunction

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0446

P0446 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0446 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0446 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The engine control module (ECM) sets this code when it detects an electrical or functional fault in the EVAP vent control circuit. The vent valve allows fresh air to enter the EVAP system during purge cycles and closes during system self-tests to check for leaks. If the ECM detects an open circuit, short, or improper valve operation, it triggers this fault code.

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