EVAP Purge Control Valve Circuit
The P0443 code indicates a malfunction in the electrical circuit of the Evaporative Emission Control System (EVAP) purge control valve. The Engine Control Module (ECM) sets this code when it detects an improper voltage or resistance in the purge valve circuit, meaning the valve cannot be commanded open or closed properly.
This code is not an immediate safety hazard and will not strand you. However, it will cause increased emissions, slightly reduced fuel economy, and will fail an emissions test, so it should be addressed soon.
Common symptoms
- Illuminated Check Engine Light (MIL)
- Slight decrease in fuel economy
- Rough idle or hesitation (if the valve is stuck open)
- Noticeable fuel odor around the vehicle
- Failure to pass a state emissions inspection
Likely causes
- Faulty EVAP purge control valve (internal solenoid failure)
- Damaged, corroded, or loose wiring connector at the purge valve
- Broken or shorted wiring in the purge valve circuit
- Blown fuse providing power to the EVAP circuit
- Faulty Engine Control Module (ECM) (rare)
What to check before replacing parts
Visually inspect the purge valve wiring and connector
Look for: Look for frayed wires, corrosion on the pins, or a disconnected plug at the purge valve.
Measure the purge valve internal resistance
Look for: Use a multimeter to check the resistance of the valve solenoid. An open circuit (OL) or an out-of-spec reading indicates a failed internal solenoid.
Check for power at the purge valve connector
Look for: With the ignition ON (engine off), use a multimeter to verify there is 12-volt battery power at the supply side of the disconnected purge valve harness.
Test the control circuit for continuity and shorts
Look for: Test the ground/control wire from the ECM to the valve connector for continuity, and ensure it is not shorted to ground or voltage.
Command the valve using a bi-directional scan tool
Look for: Command the purge valve on and off with the scan tool. Listen or feel for a distinct click from the valve, which verifies the ECM can successfully control it.
This page explains the generic P0443 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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