P0456 - EVAP System Small Leak

The Technical Definition: The Engine Control Module (ECM) has detected a very small leak in the Evaporative Emissions System.

Common Symptoms: Check engine light is on. Usually, there are no noticeable performance issues or changes in how the Jeep drives.

Typical Fix: 90% of the time, this is just a loose, dirty, or failing gas cap. Clean the seal on the gas cap and the filler neck, click it tight, and clear the code. If it returns, the next culprit is often the ESIM (Evaporative System Integrity Monitor) switch or a cracked vacuum line near the EVAP canister.