2014 Jeep Grand Cherokee - P0456 Small EVAP Leak

Question

Struggling with a persistent P0456 'Small EVAP Leak' on my 2014 Grand Cherokee. I've already replaced the gas cap with an OEM Mopar one because that's usually the culprit, but the light came back on after about two days of driving.

I don't smell any raw gasoline around the vehicle. I've looked at the lines under the hood and nothing looks obviously cracked or disconnected. This car has the capless fuel filler neck, so I'm not even sure if the 'gas cap' warning is relevant or just a generic Jeep message for an EVAP fault. It's driving me crazy because I can't pass inspection with the CEL on.

MisfireMatt · Answer

Check the EVAP purge valve located on the driver's side of the engine. These Pentastar engines have a high failure rate on the purge solenoid where they leak internally. If you can blow air through it while it's disconnected and unpowered, it's bad.

HondaHankk · Answer

✅ Confirmed fix: The issue was the ESIM (Evaporative System Integrity Module) located on the side of the charcoal canister above the rear axle. These plastic modules have a small weighted diaphragm that often sticks or the o-ring seal fails.

I replaced the ESIM detector (Part #310601) and used a smoke machine to verify there were no other leaks in the plastic lines running to the front. The smoke actually started pouring out of the ESIM body itself during the test. Replaced the unit and the Monitor cleared after two drive cycles.

2014 Jeep Grand Cherokee - P0456 Small EVAP Leak

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