OBD-II Code P0445 — What It Means & How to Fix It

What Does This Error Mean?

P0445 means the PCM detected a short circuit in the EVAP purge control valve circuit. Unlike P0444 which is an open circuit, P0445 means there is an unwanted electrical path — usually to ground or to power. The PCM cannot properly control the purge valve when the circuit is shorted. This can cause rough idle, fuel smell, or difficulty maintaining a steady idle.

Affected Models

All 1996+ gasoline vehicles with EVAP emission control systems
Common in GM vehicles with wiring near heat sources
Common in Ford and Chrysler vehicles with aging EVAP harness wiring
Common in Toyota and Honda vehicles with high mileage
Common in any vehicle where the purge valve wiring runs near exhaust components

Common Causes

Short circuit to ground in the purge valve control wire
Short circuit to power (voltage) on the purge valve signal wire
Failed purge valve solenoid with a shorted internal winding
Chafed wiring harness where two wires have worn through insulation and are touching
Damaged wiring near exhaust components where heat melted the insulation

How to Fix It

Locate the EVAP purge control valve on your engine. It is typically a small solenoid near the intake manifold or firewall with two hose connections and a two-wire electrical connector. Inspect it and the surrounding wiring visually for obvious damage.

Heat damage from nearby exhaust components is a very common cause of shorted wiring on EVAP components.
Unplug the purge valve connector and check if the short circuit code clears. If the fault code disappears after unplugging the valve, the short is inside the valve solenoid or in the wiring downstream of the connector.

If the code remains after unplugging the valve, the short is in the wiring between the PCM and the valve connector — not inside the valve itself.
Test the purge valve solenoid resistance with a multimeter. Set it to ohms and measure across the two valve terminals. A shorted solenoid will read near zero ohms. Normal is typically 14-30 ohms. Near-zero resistance confirms the valve has a shorted winding.

A reading of zero ohms also means the valve will draw excessive current when energized, which could damage the PCM driver circuit over time.
Inspect the wiring harness from the purge valve connector back toward the PCM. Look for areas where two wires have rubbed through their insulation and are touching. Pay close attention near heat sources and sharp metal edges.

Use a wiring diagram for your vehicle to identify which wires are in the purge valve circuit. This helps you focus the inspection on the right section of the harness.
Replace the purge valve if solenoid resistance is near zero. If the short is in the wiring, repair or replace the damaged section with appropriately rated wire and proper connectors. Clear fault codes and perform several drive cycles to confirm the repair.

After the repair, the EVAP system monitor must complete a full drive cycle check. This can take 1-3 days of normal driving to confirm.

When to Call a Professional

A short circuit is harder to find than a simple open circuit. Tracing a short through a wiring harness requires a wiring diagram and sometimes a short finder tool. A shop can resolve this faster with proper tools. Diagnosis typically costs $80-$130. Purge valve replacement is $50-$150; wiring repairs vary by the extent of damage.

Frequently Asked Questions

What is the difference between P0444 and P0445?

P0444 is an open circuit — the electrical path is broken. P0445 is a short circuit — there is an unintended electrical connection. Both prevent the PCM from properly controlling the purge valve. The diagnostic approach differs — P0444 looks for broken wires; P0445 looks for wires touching or grounding where they should not.

Can a shorted purge valve damage the PCM?

Yes, potentially. The PCM sends current through the purge valve to control it. If the valve solenoid is shorted, it draws more current than the PCM driver circuit is designed for. Prolonged operation with a shorted load can damage the PCM output driver. Replace a shorted purge valve promptly.

Will P0445 cause my car to fail an emissions test?

Yes. Any stored fault code will cause an OBD-II emissions test failure. Additionally, a shorted purge valve prevents the EVAP monitor from completing. An incomplete EVAP monitor is also a failure on most state emissions tests. Fix P0445 and allow several drive cycles before your test.