What Does P0459 Mean?
The EVAP purge control valve circuit is reading a higher voltage or current than expected by the PCM. This high circuit condition typically indicates an open ground, an open solenoid coil, or the control wire is shorted to battery voltage. The purge valve cannot be properly controlled, and the EVAP system will not purge fuel vapors as designed. The check engine light will illuminate.
Common Causes
30%
Open circuit in the purge valve solenoid coil (burned-out winding)
25%
Open ground wire in the purge valve circuit
20%
Control wire shorted to battery voltage in the harness
15%
Corroded or disconnected connector at the purge valve
10%
PCM output driver stuck high or damaged
Diagnostic Steps
1
Disconnect the purge valve connector and measure solenoid coil resistance. Normal is 20-40 ohms. An infinite (OL) reading means the coil is open and the valve must be replaced.
2
With the valve disconnected, check the harness ground wire for continuity back to the PCM. Should read under 2 ohms. An open ground circuit will cause a high voltage reading.
3
Check the control wire for a short to battery voltage: measure from the control wire to battery positive with the harness disconnected at both ends. Should read OL.
4
Inspect the purge valve connector for corrosion, backed-out pins, or broken terminal locks that could cause an intermittent or permanent open circuit.
5
If wiring and valve test good, verify the PCM ground-side switching signal using a lab scope at the PCM connector while commanding the purge valve on/off via bidirectional controls.
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
The EVAP purge control valve circuit is reading a higher voltage or current than expected by the PCM. This high circuit condition typically indicates an open ground, an open solenoid coil, or the control wire is shorted to battery voltage. The purge valve cannot be properly controlled, and the EVAP ...
The most common cause of P0459 (Evaporative Emission System Purge Control Valve Circuit High) is: Open circuit in the purge valve solenoid coil (burned-out winding)
Typical repair costs for P0459 range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The EVAP purge valve high circuit is an emissions-related code. The vehicle will operate normally, but fuel vapors are not being purged properly. Repair for emissions compliance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0459 to identify the root cause.
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Quick Info
Category
Powertrain
System
EVAP / Emissions System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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