P0445
Evaporative Emission Control System Purge Control Valve Circuit ShortedP0445 is a generic OBD-II powertrain diagnostic trouble code: Evaporative Emission Control System Purge Control Valve Circuit Shorted. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0445 means
P0445 is stored when the PCM detects a short circuit in the EVAP canister purge control valve circuit. The purge valve solenoid is commanded by the PCM using a pulse-width modulated ground signal. A short to ground (or an internally shorted coil) causes excessive current to flow through the driver circuit, which the PCM detects as an abnormally low resistance path and logs P0445.
This code is the electrical opposite of P0444 (open circuit). Where P0444 means no current is flowing, P0445 means current is flowing through an unintended path. A shorted wiring harness — where the signal wire contacts the chassis or another ground — or an EVAP purge solenoid whose coil has failed with near-zero resistance are the two most common causes. The PCM's internal driver may also shut down to protect itself from the overcurrent condition.
Driveability symptoms are usually minimal. The engine will run normally on metered fuel, but vapour purging will be disrupted. If the valve is held open by the short, a large unmetered vapour charge can cause a momentary rich stumble or rough idle at low load. The MIL illuminates and the EVAP monitor will be flagged incomplete.
Common causes
Most-frequently reported root causes when P0445 is logged.
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1
Internally shorted purge valve solenoid coil (near-zero resistance between terminals).
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2
Signal or control wire chafed against the chassis or engine block, creating a short to ground.
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3
Pinched wiring in the harness routing near hot or sharp components.
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4
Water or coolant intrusion into the purge valve connector causing a conductive short between pins.
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5
Damaged insulation on two adjacent wires that allows them to contact each other.
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6
Failed PCM output driver that is permanently grounding the circuit (rare, after ruling out external wiring).
Symptoms drivers notice
How to diagnose P0445
A typical diagnostic flow when this code is present.
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1
Retrieve and record all codes; distinguish P0445 (short) from P0444 (open) before testing.
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2
Disconnect the purge valve connector and measure solenoid coil resistance — a reading at or near 0 ohms confirms an internally shorted valve coil.
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3
With the valve disconnected, check the harness-side control wire for continuity to chassis ground using a multimeter; any continuity indicates a wiring short to ground.
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4
Inspect the purge valve wiring harness along its entire routing for chafing, melted insulation, or pinch points near the exhaust or engine block.
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5
Check the connector for signs of water ingress, corrosion, or melted plastic that could bridge two terminals.
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6
If the wiring harness and valve both test normal, use a lab scope to monitor the PCM driver output — a failed PCM driver will show a constant low signal rather than a modulated pulse.
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7
Repair any shorted wiring or replace the faulty purge valve, then clear the code and verify the EVAP monitor completes.
Related powertrain codes
- P0400 — Exhaust Gas Recirculation Flow Malfunction
- P0401 — Exhaust Gas Recirculation Flow Insufficient Detected
- P0402 — Exhaust Gas Recirculation Flow Excessive Detected
- P0403 — Exhaust Gas Recirculation Circuit Malfunction
- P0404 — Exhaust Gas Recirculation Circuit Range/Performance
- P0405 — Exhaust Gas Recirculation Sensor A Circuit Low
Frequently asked questions
What is the difference between P0445 and P0444?
P0445 is a short circuit (very low resistance — wiring shorted to ground or coil failed shorted), while P0444 is an open circuit (very high resistance — broken wire, disconnected plug, or open coil). Measure coil resistance first: near-zero points to P0445 root cause; open (OL) points to P0444.
Can a shorted purge valve damage the PCM?
Modern PCMs include internal current-limiting protection on solenoid driver circuits. A sustained short to ground can stress the driver and eventually cause it to fail, which is why prompt diagnosis is important. If the PCM driver has already been damaged, simply replacing the valve or wiring may not clear the code without also repairing the PCM.
Is P0445 serious?
It is low severity in terms of immediate driveability — the engine will generally continue to run normally. However, a sustained short can damage the PCM driver circuit over time, and the vehicle will fail an emissions test. Repair is straightforward in most cases: replace the shorted purge solenoid or repair the damaged wire.
How do I confirm the purge valve is shorted rather than the wiring?
Unplug the purge valve connector from the harness, then measure resistance directly across the two solenoid pins on the valve itself. If resistance is at or near 0 ohms, the valve coil is internally shorted and the valve needs replacement. If the valve reads normal resistance but the harness wire shows continuity to ground with the valve unplugged, the short is in the wiring.
Disabling P0445 in software
RaceTune can permanently disable P0445 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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