EVAP System Purge Control Valve A Circuit High
What it means
P0459 means the ECM has detected a high-voltage (open or short-to-voltage) electrical fault in the control circuit for the EVAP purge valve, which meters fuel vapour from the charcoal canister into the intake. It's almost always a valve or wiring fault. The engine usually runs normally — the practical effects are the check-engine light and a likely emissions-test failure, with occasional rough idle if the valve sticks open.
Can I keep driving? Safe to drive — this is an evaporative-emissions circuit fault. The engine runs normally in most cases; the light stays on and it can fail an emissions test.
Common symptoms
What you'll notice
- Check-engine light on
- Fails an emissions test
- Usually no change in how the engine runs
- Occasional rough idle if the purge valve is stuck open
Common causes
Most likely first
- Failed EVAP purge control valve (electrical fault reading high)Likely
- Open or short-to-voltage in the purge valve control wiringCommon
- Corroded or loose connector at the purge valveCommon
- Failed engine control module (rare)Less often
How to diagnose & fix
Work through it in order
- Confirm the code and command the purge valve with a scan tool to see if it responds.
- Inspect the purge valve connector and wiring for an open, short to voltage, or corrosion.
- Measure the purge valve solenoid's resistance against spec.
- Replace the purge valve if it's out of spec, or repair the circuit. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0459?+
Can I just clear P0459?+
Related codes
Often seen with P0459
Read & clear P0459 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.