Evaporative Emission Control System Purge Control Valve Circuit High
What does P0459 mean?
The P0459 code means the vehicle's onboard diagnostic system has detected: Evaporative Emission Control System Purge Control Valve Circuit High. This is a low severity code.
Common Symptoms
- Check Engine Light illuminated
- Possible rough idle after refueling
- Fuel vapor odor
- Failed emissions inspection
Probable Causes (Ranked by Likelihood)
- Short to voltage in purge valve control wire Very High
- Open ground circuit to the purge valve High
- Failed purge valve solenoid with high resistance Moderate
- ECM driver circuit fault Low
Step-by-Step Diagnostic Procedure
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Check for voltage on the purge valve control wire with the key on, engine off, and the valve commanded off -- should be near 0V
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Verify the purge valve ground wire has continuity to chassis ground
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Measure purge valve solenoid resistance -- readings above 60 ohms indicate a failing coil
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Inspect wiring for chafing against power sources such as the alternator output or battery cables
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Test with a known-good purge valve to confirm
Frequently Asked Questions
Can I drive with code P0459?
Yes. This electrical circuit code does not affect drivability or safety. The purge valve may be stuck on or off, but the engine will compensate. Repair before emissions testing.
What does circuit high mean for P0459?
Circuit high means the ECM detects higher voltage than expected on the purge valve control circuit. This can be caused by a short to a power source, an open ground, or a high-resistance solenoid coil.
How do I find a short to voltage in the purge valve wiring?
Disconnect the purge valve and ECM connectors, then use a multimeter to check for voltage on the signal wire. Trace the harness looking for areas where it contacts power wires or hot components.