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P0444Evaporative Emission Control System Purge Control Valve Circuit Open

The engine computer sees an open (broken) electrical circuit to the EVAP purge control valve, so it cannot command purge flow.

Definition

The PCM controls the EVAP purge valve with a driver circuit and continuously monitors circuit continuity by watching the voltage on the control wire. P0444 sets when the PCM detects an open circuit — no current flows when the solenoid is commanded on — meaning a broken wire, corroded connector, or open solenoid winding. The engine typically runs normally, but stored fuel vapors are never purged from the charcoal canister, the MIL illuminates, and the vehicle will fail an emissions inspection; a saturated canister can eventually cause fuel odor.

Common causes

  • Failed (open) purge solenoid winding
  • Broken or chafed wire in the purge valve harness
  • Corroded, backed-out, or damaged connector terminals at the purge valve
  • Blown fuse on the solenoid's ignition-voltage feed
  • Rodent damage to underhood wiring
  • Faulty PCM driver circuit (uncommon)

Common misdiagnoses

  • Gas cap replaced for what is purely an electrical circuit fault
  • Charcoal canister replaced when the solenoid or wiring is at fault
  • Purge valve replaced repeatedly when the harness or connector has the open
  • PCM replaced before wiring continuity was verified

Troubleshooting steps

  1. 1.Check for battery voltage at the purge valve connector

    With key on, one terminal should show system voltage (about 12.6 V); no voltage means an open feed wire or blown fuse.

  2. 2.Measure the purge solenoid coil resistance

    Most purge solenoids read roughly 20-40 ohms; an open (OL) reading confirms a failed solenoid.

  3. 3.Test the control circuit back to the PCM

    With the connector unplugged, check continuity from the valve's control terminal to the PCM connector; wiggle the harness to expose intermittent breaks.

  4. 4.Command the valve with a scan tool

    Use bidirectional control to cycle the purge solenoid and listen/feel for a click; no actuation with good power and wiring points to the solenoid or PCM driver.

  5. 5.Inspect the connector for corrosion and terminal tension

    Green corrosion or loose terminal fit causes intermittent opens; repair terminals rather than just re-seating the connector.

  6. 6.Clear the code and verify purge operation

    Watch commanded purge duty and short-term fuel trim at cruise; trims should shift slightly when purge ramps up, confirming the circuit is restored.

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