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P0444 — Evap System Purge Control Valve Circuit Open

Generic OBD-II · all makesPowertrain (engine & transmission)

P0444 indicates that the powertrain control module (PCM) has detected an open circuit in the evaporative emission (EVAP) purge control valve solenoid. This means the solenoid's electrical circuit is incomplete, preventing the valve from opening to allow fuel vapors to be purged into the engine.

Symptoms

What causes it — most likely first

1. Faulty purge control valve solenoid (open internal coil)

The solenoid's internal winding can break or develop an open circuit, which is the most common failure. This prevents current flow and triggers the code.

2. Damaged or corroded wiring/connector at the purge valve

Wires leading to the purge valve can chafe, break, or corrode, especially near the valve or along the engine harness. A loose or unseated connector can also cause an open circuit.

3. Open circuit in the PCM-to-purge valve harness

A break in the control wire between the PCM and the purge valve, often due to rodent damage or physical stress, can cause the open circuit.

4. Blown fuse or faulty relay in the purge valve power circuit

If the purge valve receives power through a fuse or relay, a blown fuse or failed relay can interrupt the circuit, though this is less common than valve or wiring issues.

5. Failed PCM (engine control module) – rare

In very rare cases, an internal driver failure in the PCM can cause an open circuit. This should only be considered after thoroughly testing the valve, wiring, and power supply.

How it's diagnosed

  1. Retrieve and record all diagnostic trouble codes, then clear them and perform a test drive to see if P0444 returns immediately.
  2. Visually inspect the purge control valve connector and wiring for damage, corrosion, or loose pins. Repair or replace as needed.
  3. Disconnect the purge valve connector and measure resistance across the valve solenoid terminals. Compare to manufacturer specification (typically 10–30 ohms); an open reading (OL) confirms a faulty valve.
  4. With the ignition on and engine off, check for battery voltage at the purge valve connector on the power supply wire (if applicable) and verify a good ground path. Use a wiring diagram to identify the correct pins.
  5. If voltage and ground are present but the valve resistance is good, check for continuity in the control wire from the PCM to the valve connector. An open circuit indicates a harness break.
  6. If all wiring and the valve test good, suspect a PCM issue. Perform a PCM output test (if scan tool supports it) or consult a professional for further diagnosis before replacing the module.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0440 — Evap SystemP0441 — Evap System Incorrect Purge FlowP0442 — Evap System Leak Detected Small LeakP0443 — Evap System Purge Control Valve CircuiP0445 — Evap System Purge Control Valve CircuiP0446 — Evap System Vent Control Circuit

Frequently asked

Is it safe to drive with a P0444 code?

Yes, it is generally safe to drive short distances. The EVAP system only affects emissions, not engine performance or safety. However, the check engine light will remain on, and the vehicle may fail an emissions test. It's best to repair it soon to prevent fuel vapor release.

Can a loose gas cap cause P0444?

No, P0444 is a circuit open code for the purge control valve solenoid. A loose gas cap typically triggers large leak codes (P0455) or small leak codes (P0456), not an open circuit code.

Do I need to replace the PCM for P0444?

Almost never. The PCM is rarely the cause of P0444. The most common failures are the purge valve solenoid itself or a wiring/connector issue. Only consider the PCM after thoroughly testing the valve, wiring, and power supply with a multimeter.

Will P0444 clear itself after replacing the purge valve?

If the repair is successful, the code may clear after several drive cycles with the monitor running. However, it's recommended to clear the code with a scan tool after repair to confirm the fix and reset the readiness monitors.