Diagnostic trouble code P0442 indicates a small leak has been detected in the Evaporative Emission (EVAP) System.  Sealed fuel systems found on today's vehicles are intended to prevent unburned fuel vapors from escaping the fuel system.  Gasoline vapors, if allowed to evaporate into the atmosphere, will react chemically with sunlight and become smog.   

U.S. Vehicles built after 1995 (OBDII) will store diagnostic trouble codes, and illuminate the "Service Engine Soon" light if a leak or other problem is detected in the EVAP system.



Most of the time, P0442 code will cause no noticeable drivability symptoms.


Possible Causes:

  • Defective, loose, or missing gas cap - Check gas cap seal for cracks
  • Vapor leak in gas tank, charcoal canister, hoses, etc.
  • Defective canister vent or purge solenoid
  • Defective fuel tank pressure sensor


Similar Codes:

  • P0440 - EVAP System Malfunction
  • P0441 - EVAP System Insufficient Purge
  • P0443 - EVAP System Purge Solenoid Circuit Malfunction
  • P0446 - EVAP System Vent Control Circuit Malfunction 
  • P0449 - EVAP System Vent Solenoid Circuit Malfunction
  • P0450 - EVAP System Pressure Sensor Malfunction
  • P0451 - EVAP System Pressure Sensor Performance
  • P0452 - EVAP System Pressure Sensor Low
  • P0453 - EVAP System Pressure Sensor High
  • P0455 - EVAP System Large Leak Detected
  • P0456 - EVAP System Small Leak Detected
  • P0457 - EVAP System Leak Detected
  • P0496 - EVAP System Flow Detected During Non-Purge