P0445
PowertrainEvaporative Emission Control System Purge Control Valve Circuit Shorted
There's an electrical short in the wiring or solenoid that controls the EVAP purge valve, the part that lets stored fuel vapour from the charcoal canister get drawn into the engine and burnt off. For you, this is almost always a warning light job rather than a breakdown job. The car drives normally, but the EVAP system isn't switching properly and that puts the emissions side out of action, which matters at MOT time.
ⓘ Information only. This page provides general educational information about fault code P0445. 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 P0445 mean?
P0445 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Evaporative Emission Control System Purge Control Valve Circuit Shorted.
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:
- • Check engine light on, usually with nothing else wrong that you can feel
- • A faint whiff of petrol around the back of the car, more obvious after the engine's been running
- • Fuel economy might drop a touch, though most people never spot it
- • Refuelling can become a pain, the pump nozzle keeps clicking off before the tank's full
- • No effect on starting, idle, or power. The engine behaves itself
Possible causes
Causes commonly associated with P0445, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Chafed or melted wiring in the purge valve circuit, usually where the loom rubs on something or runs near heat. This is the most common cause of a true shorted-circuit code rather than a leak
- 2. Purge valve with a shorted solenoid coil inside it. The valve itself has failed electrically
- 3. Corroded or water-damaged connector at the valve, very common on cars that spend their life outdoors in British weather
- 4. Purge valve gummed up with fuel residue or canister dust, sticking and dragging the circuit out of spec
- 5. Charcoal canister saturated and pushing back through the system, more likely if someone's been topping up past the click
- 6. ECM output driver gone down on the purge control side. Rare, and worth ruling everything else out before you go there
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 freeze frame data alongside the code so you know what the car was doing when it logged. A cold-start one-off behaves very differently from a constant fault
- 2. Get under the bonnet and follow the purge valve wiring by hand, checking for chafe points, melted insulation, and a connector full of green corrosion. This finds a big share of them
- 3. Unplug the valve and measure resistance across the coil with a multimeter. A reading near zero ohms means the coil's shorted internally and the valve needs replacing
- 4. With the valve disconnected, check the two pins for a short to earth or to battery voltage. That tells you the fault is in the loom, not the valve
- 5. Back-probe the connector and command the purge valve with a scan tool to confirm the ECM is actually pulsing it. No switching points at the wiring or the driver
- 6. If the wiring and valve all check out clean, put a smoke machine on the EVAP system to catch anything the electrical tests missed before condemning the canister
Common questions about P0445
How do I work out whether it's the valve, the wiring, or something else on my own car? +
Start with the multimeter test across the valve coil. If you read close to zero ohms with it unplugged, the valve is shorted internally and that's your answer. If the coil reads a sensible value (usually somewhere around 20-40 ohms depending on the make), the valve is fine and the fault is in the wiring or connector, so go looking for chafe and corrosion. A saturated canister tends to come with refuelling trouble and that petrol smell, whereas a pure circuit short usually gives you the light and not much else.
Can I just clean the purge valve and connector myself instead of replacing parts? +
Cleaning a sticky valve with a bit of brake cleaner and clearing out a corroded connector is a fair thing to try, and it sometimes sorts a marginal one. But P0445 specifically points at an electrical short, and you can't clean a coil that's failed internally back to life. If the connector cleans up and the resistance reads correctly afterwards, you've likely cracked it. If not, the valve or a loom repair is the real fix.
If I clear the code does it stay gone, or come straight back? +
Depends entirely on what caused it. A genuine internal short or a damaged connector will bring the light back within a drive cycle or two, because the ECM keeps checking the circuit and keeps finding the fault. A one-off triggered by a damp connector that's since dried out might clear and stay clear. Clearing it is a useful test in its own right, watch whether it returns and how quickly.
What's the harm in just leaving it and carrying on? +
Mechanically you'll be fine for a good while, the engine doesn't depend on this circuit to run. The two real costs are emissions and your MOT. With the EVAP system out of action you're venting more fuel vapour than you should, and if that engine light is on when you roll up for the test it can sink your result. There's also the petrol smell and the awkward refuelling to live with. Cheap to sort if it's a connector or valve, so most people would rather fix it than nurse it.
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 →