What Does the P0456 Code Mean? The P0456 is a generic code stating that the Engine Control Module (ECM) detected a small leak from the evaporative system. This leak was detected during a self-test. For the code to come on, the test must fail two times in a row before the Check Eng...
Most often, the message reveals that the gas cap is loose or damaged. It can also mean that you filled up the fuel tank while the engine was running, that there’s an EVAP leak or the car has a bad EVAP purge control valve. Otherwise, the EVAP lines may be clogged or there could ...