ECM checks the valves’ tightness and system pressure, and if the 0.2-0.4 inches leakage is detected, you can see the P0442 code. All codes from P0440 to P0457 refer to EVAP problems. A complete check-up of the EVAP system could take about an hour of labor and cost you $75-150....
2001 Saturn L200 P0440 Code- The P0440 trouble code just won't go away. The gas cap is good, what next? 2002 Toyota Corolla P0442 DTC Code- I can't afford the $160 diagnosis plus parts right now, can I wait a while to get this fixed?