NGC

Test 1 - 2:

Test 3 - 4:

SYMPTOM
P0456-EVAP SYSTEM SMALL LEAK

WHEN MONITORED
Ignition off Fuel Level less than 88%. Ambient Temperature between 4 °C to 43 °C (39 °F to 109 °F).

SET CONDITION
Due to temperature changes a vacuum is created in the fuel tank and EVAP system. With the EVAP system sealed, the PCM monitors the NVLD switch. If the NVLD switch does not close within a calibrated amount of time an error is detected.

POSSIBLE CAUSES
- Good trip equal to zero
- Leak at Gas Cap
- Vehicle History and Service Bulletin Investigation
- Visual and physical inspection
- Verify Evaporative Emission Leak
- EVAP Purge Solenoid Operation
- Evaporative Emission Leak Detection
- Gas Cap
- NVLD