P0447Powertrain
Powertrain · SAE
EVAP System — Vent Control Circuit Open
Meaning
The ECU detects an open circuit in the control circuit of the canister EVAP vent valve. The solenoid receives no command signal due to an electrical interruption.
Common causes
- Broken vent valve control wire
- Disconnected or corroded vent valve connector
- Internally open vent valve coil
- Failed ECU driver for the vent valve circuit
- Blown fuse in the vent valve circuit
Symptoms
- Malfunction indicator lamp (MIL) on
- EVAP system inoperative (vent valve uncontrolled)
- EVAP leak detection monitor failure
- Fuel vapor odor near the canister
- Generally no driveability symptoms
Severity
Moderate: the vent valve is not controllable, leak detection tests fail, and evaporative emissions are elevated.
What to do
- Check circuit continuity between the valve connector and the ECU pin
- Measure vent valve coil resistance (typically 22–32 Ω; infinite reading indicates open coil)
- Verify supply voltage and command signal at the connector
- Inspect connector and wiring for corrosion or breaks
- Replace the vent valve or repair the wiring based on findings