| DTC Data Sheet | |
| System | Powertrain |
| Standard | SAE J2012 / ISO 15031-6 |
| Fault type | Circuit High |
| Official meaning | Evaporative Emission System Purge Control Valve Circuit High |
The PCM has detected a high-side fault on the EVAP purge valve circuit — voltage is sitting above the expected range, indicating an open circuit or a short to power on the valve coil.
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P0459 Quick Answer
The PCM has detected a high-side fault on the EVAP purge valve circuit — voltage is sitting above the expected range, indicating an open circuit or a short to power on the valve coil. The first thing to check is engine oil level, condition, and viscosity — many P045-range faults are oil-driven before they are electrical.
What Does P0459 Mean?
Evaporative Emission System Purge Control Valve Circuit High. The PCM has detected a high-side fault on the EVAP purge valve circuit — voltage is sitting above the expected range, indicating an open circuit or a short to power on the valve coil.
Symptoms
- Check engine light
- No noticeable drivability symptoms in most cases
- EVAP monitor will not run
- Possible related EVAP codes (P0440, P0455) if the valve cannot purge canister vapors
Common Causes
- Open in the purge valve solenoid coil (failed internally)
- Open wiring between the PCM and the purge valve
- Short to power (12 V) on the control wire
- Disconnected or backed-out connector at the purge valve
- Damaged PCM internal driver
Diagnosis Steps
You’ll need a scan tool capable of reading live powertrain data, a digital multimeter, and access to the wiring diagram for the specific platform.
- Locate and disconnect the purge valve.
- Measure resistance across the valve terminals — open reading or wildly high resistance indicates an internally failed solenoid.
- Verify 12 V supply at the connector with key on.
- Confirm continuity from the PCM control pin to the purge valve connector — open trace flags this code.
- Check for short to 12 V on the control wire by isolating the PCM and back-probing.
Possible Fixes
- Replace the EVAP purge valve
- Repair open or shorted-to-power wiring
- Connector repair
Can I Still Drive With P0459?
The vehicle will usually still drive with P0459 stored, but performance and fuel economy are degraded. The fault disables or limits the affected actuator, and the PCM may inhibit emissions monitors. Drive to a workshop, but don’t ignore the code long-term — VVT and EVAP failures often cascade into related faults if left untreated.
How Serious Is This Code?
P0459 is a moderate-priority fault. It will not prevent the engine from running but will affect drivability, emissions, and over time can damage related components (cam phaser wear, catalytic converter on EVAP-related codes). Address within a few drive cycles.
FAQ
Will P0459 clear itself?
Only if the underlying fault was intermittent and self-corrected. Most P0459 root causes (failed solenoid, wiring damage, blocked screen) are persistent and require physical repair.
Can I clear P0459 without fixing it?
You can clear it with a scan tool, but it will return as soon as the fault condition reappears — typically within one or two drive cycles.
Is P0459 related to other codes?
Often, yes. Cam-position and EVAP faults frequently set adjacent codes — if P0459 is present, scan for related codes in the same range and address them as a group rather than one at a time.