P0442

Refer to EVAP System Overview.

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

SYSTEM DESCRIPTION
The EVAP system includes the following components:
^ The fuel tank.
^ The EVAP vent valve.
^ The EVAP canister purge valve.
^ The EVAP Canister.
^ The fuel pipes and hoses.
^ The EVAP vapor and purge pipes.
^ The EVAP fresh air vent hose.
^ The fuel fill cap.

The EVAP SMALL LEAK TEST is based on applying vacuum to the EVAP system and monitoring vacuum decay. The PCM monitors vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP canister purge valve and the EVAP vent valve are turned on allowing engine vacuum to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP purge valve is turned off, sealing the system. A leak is detected by monitoring for a decrease in vacuum level over a given time period, all other variables remaining constant. A small leak in the system will cause DTC P0442 to be set.

CONDITIONS FOR RUNNING THE DTC
^ DTC P0443 or P0449 not active.
^ No TP, IAT, FTP, ECT or MAP sensor DTCs set.
^ System voltage is between 10 and 18 volts.
^ The DTC P0440 diagnostic test has passed.
^ Startup ECT is not more than 4°C - 30°C (39°F - 86°F).
^ Startup ECT is not more than 8°C (14°F) more than IAT startup temperature.
^ Startup IAT not more than 4°C - 30°C (39°F - 86°F).
^ Startup IAT is not more than 3°C (7°F) more than ECT startup temperature.
^ Fuel tank level is between 15 percent and 85 percent for a 0.040-0.060 leak.
^ Fuel tank level is between 30 percent and 85 percent for a 0.020 leak.
^ BARO is more than 75 kPa.
^ IAT is less than 30°C (86°F)
^ VSS below 80 MPH.

CONDITIONS FOR SETTING THE DTC
A vacuum decay condition indicating a small leak is detected during the diagnostic test.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the first trip in which the diagnostic test has been run and failed.
^ The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the MIL OFF during the first trip in which the diagnostic has been run and passed.
^ The history DTC will clear when the PCM turns off the MIL.
^ The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
The following conditions will set DTC P0442:
^ Loose or malfunctioning fuel fill cap.
^ Damaged EVAP purge or vapor pipes.
^ Damaged EVAP fresh air vent hose.
^ Malfunctioning EVAP vent valve.
^ Damaged EVAP Canister.
^ Leaking fuel tank, fuel sender assembly O-ring or pressure relief valve.
^ Leaking fuel tiller neck or seal.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
1. The powertrain On Board Diagnostic (OBD) System Check prompt you to complete some of the basic checks and store the Freeze Frame and Failure Records data on the scan tool if applicable.
15. The EVAP station is pressurizing a sensor that normally reads vacuum. The scan tool reads high pressure at 0 volts and high vacuum at 5 volts. The scan tool can only read a max pressure of 6.0 inches of H2O (0 volts), however the EVAP service station can pressurize the system to much higher pressures. The scan tool value should be with in 0.5 inch H2O of the specified value.