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What causes a purge valve failure?

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A short or open in the solenoid windings would set a purge valve circuit code.That kind of purge valve failure would set a check engine light and one of these trouble codes

A purge valve has two vacuum line ports; one vacuum line supplies fuel vapor form the charcoal canister. The other port is connected to the intake manifold or throttle body. Remove the vacuum line running to the intake or throttle body. Apply vacuum to this port and see if the purge valve holds vacuum. Then apply power and ground to the electrical terminals to see if the purge valve opens and closes properly. Also, check for charcoal granules in the valve. That’s an indication of a failed charcoal canister. If you find charcoal, you must replace the canister and flush the lines. If you replace just the clogged purge valve, it will just plug up again.

A purge valve is just a solenoid operated valve. The solenoid move a plunger that opens or closes the valve. So it can fail electrically or mechanically. Here’s what causes a purge valve failure:

P0443 – Evaporative Emission Control System Purge Control Valve Circuit
P0444 – Evaporative Emission Control System Purge Control Valve Circuit Open
P0445 – Evaporative Emission Control System Purge Control Valve Circuit Shorted

Mechanical purge valve failure

MOPAR 4891739AA purge valve

A mechanical purge valve failure is usually caused by charcoal particles in the purge valve that prevent the valve from closing properly. That’s the sign of a damaged charcoal canister. When there are charcoal particles in the purge valve, replacing just the valve will not solve the problem. You must also replace the damaged canister and flush all the charcoal particles out of the purge line.

Use a multimeter to check for open, short to ground in the purge valve solenoid windings. Also check the electrical connector to the valve for opens or short to ground conditions.

To diagnose a mechanical purge valve failure

A purge valve can also leak due to carbon deposits on the valve seat or pintle.

Diagnose a purge valve failure

If you have an electrical trouble code  — P0443, P0445, P0446

You’ll need a handheld vacuum pump and jumper leads to test it.

MOPAR 4891739AA purge valve

P0455 – Evaporative Emission Control System Leak Detected (Large Leak)
P0456 – Evaporative Emission Control System Leak Detected (Small Leak)
P0457 – Evaporative Emission System Leak Detected (Fuel Cap Loose/Off)
P1443 – Evaporative Emission Control System Control Valve

A mechanical failure would set an EVAP leak code (since the valve isn’t fully closing or opening).

Want to know the symptoms of a bad purge valve? See this post

Electrical purge valve failure