P0456Gmc Hummer-evYears: 1996 - 2026
Evaporative Emission Control System Leak Detected (Very Small Leak)
Reviewed by ASE Certified Technician
What does this mean?
Code P0456 indicates the PCM has detected a very small leak in the EVAP system, often caused by a slightly worn gas cap seal.
Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Gmc Hummer-ev models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.
Advertisement (In-Article)
Common Causes
Loose, damaged, or missing gas cap
Cracked or disconnected EVAP hose
Faulty EVAP purge control valve
Faulty EVAP vent valve/solenoid
Symptoms to Watch For
- Check Engine Light is illuminated
- Failed emissions test