P0444
PowertrainEvaporative Emission Control System Purge Control Valve Circuit Open
Most of the time this turns out to be a corroded or unplugged connector at the purge valve, or the purge solenoid itself having gone open-circuit inside. The ECU runs a small current through the purge valve to control how engine vacuum draws fuel vapour out of the charcoal canister and back into the intake. When that electrical path goes open, the ECU sees no completed circuit and logs P0444. Drivability is usually fine, so this is more of a tidy-up job than an emergency.
ⓘ Information only. This page provides general educational information about fault code P0444. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0444 mean?
P0444 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Evaporative Emission Control System Purge Control Valve Circuit Open.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on, frequently with no change in how the car drives
- • Occasional rough idle or a brief stumble just after a cold start
- • Slight drop in fuel economy on some cars, easy to miss
- • A faint smell of petrol around the back of the car near the tank or canister
- • Car won't pass the EVAP readiness monitor, which can block an emissions retest or certain inspections
Possible causes
Causes commonly associated with P0444, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Purge valve solenoid has failed with an open coil winding, the part itself is dead and won't take a current
- 2. Corroded, broken or chafed wiring in the purge valve circuit, common where the loom runs near hot or wet areas
- 3. Loose or corroded electrical connector at the valve, often just a dirty pin or one that's worked its way loose over time
- 4. Blown fuse feeding the EVAP circuit, the cheapest possible cause so check it early
- 5. Faulty driver inside the ECM/PCM controlling the valve, rare but it happens on higher-mileage cars
- 6. Vacuum line cracked or split at the purge valve, which can throw related EVAP codes alongside this one
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read the stored codes and freeze-frame data first, then unplug the purge valve connector and look hard at both halves for green corrosion, pushed-back pins or a loose lock tab. This is where a lot of P0444s are found and fixed.
- 2. Check the relevant EVAP fuse before you go any further. It's a two-minute job and saves an hour of chasing wires.
- 3. Measure the resistance across the purge valve terminals with a multimeter and compare to the workshop figure for that engine, often somewhere around 20-30 ohms. An open or wildly high reading means the solenoid is gone.
- 4. Back-probe the connector and check for voltage while commanding the valve on and off with a scan tool. No voltage points at the wiring or the ECM rather than the valve.
- 5. Run a continuity test from the ECM pin to the valve connector to confirm the wire isn't broken somewhere along its length.
Common questions about P0444
Can I keep driving with a P0444 showing? +
Yes, for the short term it's fine. This fault sits in the emissions side of things and doesn't touch anything that'll leave you stranded. You might notice a touch worse fuel economy or a slightly lumpy cold start, but the engine runs normally otherwise. Get it sorted within a few weeks rather than ignoring it, mainly because the warning light masks anything else that might crop up.
Will this stop me passing the MOT? +
The code on its own isn't an automatic fail, but a lit engine warning light during the test counts against you under the MIL check, so that's the thing to clear. There's also the EVAP readiness monitor. If the fault stops the car completing its self-tests, an emissions retest can be refused until it's done. Fix the cause, clear the light, drive a few normal trips to let the monitors reset, then book it in.
What's it likely to cost to fix? +
Depends entirely on what's wrong. A blown fuse or a clean-up of a corroded connector is pocket-change, maybe £15-£40 at an independent garage. A new purge valve is usually £30-£120 for the part plus an hour or so labour, so call it £80-£200 fitted at an independent. Wiring repairs vary with how buried the loom is. A main dealer will charge more across the board, and any job involving ECM diagnosis can climb into the mid hundreds.
How do I work out which of these is actually causing it on my car? +
Start at the valve connector. Unplug it and inspect, because corrosion and a loose plug are the cheapest and most common findings. If the connector's clean, ohm out the valve. A dead reading means the solenoid is your culprit. If the valve checks out, you're into the wiring and ECM side, so look for voltage at the connector when the valve is commanded on. Voltage present but valve not working points back at the valve or its earth. No voltage means the wire or the ECM driver. Working through it in that order stops you buying a purge valve you didn't need.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →