P0444 means the ECU has detected an “open circuit” in the purge control valve circuit — part of the EVAP system responsible for routing fuel vapors into the engine. An open circuit means the ECU’s command cannot reach the purge valve because the electrical path is broken. This typically results in the purge valve not activating at all, which can cause fuel vapor buildup, emissions issues, and occasional hard starts after refueling. In this guide, you’ll learn what P0444 means, the likely causes, how to diagnose it step-by-step, and the repairs that usually resolve the problem.
What Does P0444 Mean?
P0444 sets when the ECU sends a command to the purge control valve but receives no electrical response due to a completely open circuit. Unlike P0443, which can involve shorts or general electrical faults, P0444 specifically points to a broken or disconnected wire, failed purge valve coil, open connector, or damaged harness. Because the valve cannot energize, the EVAP system cannot route vapors properly, preventing the EVAP monitor from completing.
Although this code rarely causes major drivability issues, it impacts emissions control and may lead to fuel odors or rough starting after filling the tank. The root cause is nearly always electrical, not a leak.
Quick Reference
- OBD-II Family: P-Code (Powertrain)
- Scope: Generic
- System: EVAP (Evaporative Emission Control)
- Difficulty Level: Easy to Intermediate
- Estimated Repair Cost: €20–€150
- Last Updated: 2025-11-24
Real-World Example / Field Notes
On many Hyundai, Kia, and Ford vehicles, P0444 appears when the purge valve harness is left unplugged after routine service. One Hyundai Elantra case involved a customer who had the intake removed for cleaning; the purge valve connector wasn’t reattached fully afterward. The ECU detected an open circuit and set P0444 immediately. Plugging in the connector and cleaning the terminals solved the issue. Other times, rodents chew the purge valve wires, leaving the circuit open.
Symptoms of P0444
- Check Engine Light: The primary visible symptom.
- No clicking from purge valve: Valve cannot energize due to open circuit.
- Hard start after refueling: Vapors may flood the intake if the purge valve is stuck open physically.
- Fuel smell: EVAP vapors may not be purged efficiently.
- Failed emissions test: EVAP monitor will not complete until the circuit is restored.
Common Causes of P0444
Most Common Causes
- Unplugged purge valve connector.
- Broken or open wiring between the purge valve and ECU.
- Failed purge valve coil (open internal winding).
- Corroded connector terminals preventing electrical contact.
- Blown EVAP-related fuse (varies by vehicle).
Less Common Causes
- ECU driver circuit failure (rare).
- Rodent damage to EVAP wiring or insulation.
- Aftermarket tuning or engine modifications affecting wiring routing.
- Connector lock tabs broken, causing intermittent disconnection.
- Purge valve replaced with incorrect-resistance aftermarket part.
Diagnosis: Step-by-Step Guide
Begin with simple checks, then move on to electrical testing to confirm the open circuit location.
Tools You’ll Need: OBD-II scanner with active test capability, multimeter, wiring diagram, test light, and basic tools.
- Inspect the purge valve connector. Ensure it is fully seated and locked in place.
- Command the purge valve with a scan tool. No audible clicking suggests an electrical open.
- Test for voltage at the connector. Use a multimeter to confirm power is present.
- Check ground side of the circuit. Ensure the ECU driver circuit is providing proper ground.
- Measure coil resistance. A healthy purge valve typically measures 20–40 ohms. Infinite resistance = open coil.
- Perform continuity tests. Verify the wiring between the purge valve connector and ECU.
- Inspect harness routing. Look for pinch points, rodent damage, or chafed insulation.
- Check fuses. Some vehicles share EVAP circuits with other components; a blown fuse may cause an open condition.
- Use a test light. Substitute the purge valve with a test light to check whether the ECU can control the circuit.
- Verify ECU connector integrity. If wiring checks out, inspect ECU pins for corrosion or damage.
Pro Tip: If the purge valve measures open (infinite ohms), replace it before performing extensive wiring tests — a failed coil is one of the most common causes of P0444.
Possible Fixes & Repair Costs
- Plug in or reseat purge valve connector: Quick and free fix.
- Replace purge control valve: If the coil is open (€40–€100).
- Repair open wiring: Soldering or replacing damaged sections (€20–€60).
- Clean corroded connectors: Improves electrical continuity (€0–€10).
- Replace blown fuse: If relevant to the circuit (€5–€15).
- Replace ECU (rare): Only after confirming no wiring or coil issues (€200–€400).
Always test the purge valve coil and connector before replacing parts — open circuits are easy to locate with a multimeter.
Can I Still Drive With P0444?
Yes, you can drive with P0444 without immediate risk, but the EVAP system will not function correctly. You may experience mild fuel odors, rough starts after refueling, or failed emissions testing. Repair the electrical issue as soon as possible to restore proper EVAP operation.
Related Codes
- P0474 – Exhaust Pressure Sensor Intermittent
- P0473 – Exhaust Pressure Sensor High
- P0472 – Exhaust Pressure Sensor Low
- P0471 – Exhaust Pressure Sensor Range/Performance
- P0470 – Exhaust Pressure Sensor
- P0469 – EVAP Purge Flow Sensor Circuit Intermittent
- P0468 – EVAP Purge Flow Sensor Circuit High
- P0467 – EVAP Purge Flow Sensor Circuit Low
- P0466 – EVAP Purge Flow Sensor Circuit Range/Performance
- P0465 – EVAP Purge Flow Sensor Circuit
Key Takeaways
- P0444 indicates an open circuit in the purge valve electrical system.
- Most common causes include unplugged connectors, broken wiring, or an open purge valve coil.
- Driving is possible but emissions control will be compromised.
- Use coil resistance tests and continuity checks to pinpoint the open circuit.
FAQ
What causes P0444 the most?
Typically, an unplugged connector or a purge valve coil that has failed open. Wiring breaks are also common, especially near the intake manifold.
Is P0444 serious?
Not for drivability, but it prevents the EVAP system from functioning correctly and will cause emissions tests to fail. Gasoline odors may also develop.
How do I diagnose P0444?
Check the purge valve connector, test the coil for resistance, verify voltage and ground, and inspect wiring continuity. A scan tool with active tests helps greatly.
Can a bad gas cap cause P0444?
No. Gas cap issues cause leak codes like P0442 or P0455. P0444 specifically refers to an electrical issue in the purge valve circuit.
Does P0444 go away on its own?
No. Electrical open circuits do not self-correct. You must repair the wiring or purge valve to clear the code permanently.