P0459 low

Evaporative Emission Control System Purge Control Valve Circuit High

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.

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Keep driving?: Yes, but fix soon
DIY difficulty: moderate
Estimated cost: $50 - $250 (parts and labor)

Try This First ($8 Fix)

Stant 10838 OE Fuel Cap

A cracked or loose gas cap causes 60%+ of EVAP codes. This $8 replacement clears P0442, P0455, and P0457 more often than any other repair.

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Find the Leak

THIKPO Automotive Smoke Machine

If a new gas cap does not clear it, the leak is somewhere in the EVAP plumbing. A smoke machine finds the exact leak -- a cracked hose, bad seal, or stuck vent valve -- in minutes instead of guessing at parts.

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Clear the Code

ANCEL AD310 OBD-II Scanner

Clear the code after the repair. If the light stays off after 50 miles, you just saved $200+ in shop fees.

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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

Check for voltage on the purge valve control wire with the key on, engine off, and the valve commanded off -- should be near 0V
Verify the purge valve ground wire has continuity to chassis ground
Measure purge valve solenoid resistance -- readings above 60 ohms indicate a failing coil
Inspect wiring for chafing against power sources such as the alternator output or battery cables
Test with a known-good purge valve to confirm

Common Fixes by Vehicle

What techs usually find when diagnosing P0459 on specific vehicles — tap your vehicle for the fix and the exact part:

2007-2015 Chevy Silverado/GMC Sierra 1500 5.3L/6.0L moderate DIY

P0459 on GM trucks is the EVAP vent solenoid (near the rear axle, on top of the fuel tank or on the charcoal canister). The solenoid sticks open or the connector corrodes from road spray. Replace the solenoid -- AC Delco 214-2246 is the OE part. Also check the vent hose for pinches or kinks, and clean the connector with electrical cleaner.

Labor: 45 min

Common fix part EVAP Vent Control Solenoid View on Amazon→ Compare fitment at PartsGeek→

2008-2016 Chevy Malibu/Impala 2.4L/3.6L moderate DIY

P0459 on these GM sedans is almost always the EVAP vent valve shorting to ground because the dust filter on the valve gets soaked with water. GM TSB 09-06-04-026 covers the repair -- relocate the vent valve filter higher on the canister. Replace the vent valve with the updated design that includes a waterproof filter.

Labor: 1 hour

Common fix part EVAP Vent Control Solenoid View on Amazon→ Compare fitment at PartsGeek→

2010-2019 Cadillac SRX/XTS 3.6L moderate DIY

P0459 high voltage fault = vent solenoid circuit open. On the Cadillac 3.6L, the vent solenoid is on the charcoal canister behind the rear left wheel. Road salt attacks the connector pins. Replace the solenoid assembly (comes with a fresh pigtail on the OE GM part). Clear the code and run a smoke test to verify the EVAP system passes.

Labor: 1 hour

Common fix part EVAP Vent Control Solenoid View on Amazon→ Compare fitment at PartsGeek→

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.