- Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking

The fuel tank filler cap and the Purge Volume Control Valve are the more common problems that will trigger the P0442 code on Nissan vehicles.

There are factory service bulletin for the P0442 code:

All Nissan Models:
Nissan Factory Service Bulletin OBDII Code P0442

2005-2007 Nissan Pathfinder
2005-2007 Nissan Pathfinder Service Bulletin OBDII Code P0442

2007-2009 Nissan Altima Sedan
2008-2009 Nissan Altima Coupe
2007-2009 Nissan Altima Hybrid
2009 Nissan Maxima
Nissan Factory Service Bulletin OBDII Code P0442

Malfunction is detected when EVAP control system has a leak, EVAP control system does not operate properly.

- Engine Light ON (or Service Engine Soon Warning Light)
- Possible a noticeable fuel odor caused by the release of fuel vapors

The Engine Control Module (ECM) tests the Evaporative Emission (EVAP) system for the following conditions:
- Large and small leaks
- Excess vacuum
- Purge flow during non-commanded conditions
- Fuel Level and Fuel Pressure sensor faults
- EVAP Purge and Vent Valve faults
The ECM monitors the Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in the EVAP system. The ECM commands both the EVAP Purge Solenoid and the EVAP Vent Valve ON when the conditions are met in order to apply an engine vacuum to the EVAP system. The ECM commands the EVAP Purge Solenoid OFF once the system has reached a predetermined level of vacuum. This test verifies if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction.