Acura MDX P0459 EVAP Purge Control Valve Circuit High won't clear

Question

My 2012 MDX threw a Check Engine light and I'm pulling a P0459 code. The car seems to idle a bit rough right after I fill up the gas tank, but otherwise it drives fine. I am worried it won't pass emissions with the MIL on.

obd2_owl · Accepted Answer

The issue was an internal short in the EVAP Purge Control Solenoid Valve. I replaced the valve with an OEM Honda/Acura part (Part #36162-RK8-005) which cost about $95. After swapping the part and clearing the codes, the P0459 stayed off and the hard start/rough idle after fueling completely disappeared. The job took about 15 minutes with basic hand tools.

Jordan Lee · Answer

P0459 usually points to a short to voltage in the purge valve solenoid circuit. Check the wiring harness near the intake manifold for any rodent damage or chafing against the engine cover.

Rachel Nguyen · Answer

You should check the resistance of the purge solenoid itself using a multimeter. If the solenoid is shorted internally, it will trigger the 'Circuit High' condition because the ECM sees a voltage return it doesn't expect.

Marcus Bell · Answer

Disconnect the harness from the purge valve and check for 12V on the power wire with the key on. If you have power and ground is being commanded correctly but the code persists, the valve is likely stuck or electrically failed.

Acura MDX P0459 EVAP Purge Control Valve Circuit High won't clear

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