P0442

CIRCUIT DESCRIPTION
The EVAP small leak test applies vacuum to the EVAP system and monitors vacuum decay. The control module monitors the fuel tank pressure sensor signal to determine the vacuum decay rate. At an appropriate time, the EVAP canister purge valve and the EVAP vent valve are turned ON. This allows the engine to draw vacuum on the EVAP 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 the vacuum level during a given time period. If the system detects a leak larger than a calibrated amount, DTC P0442 will set.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0440, P0443, P0449, P0452, P0453, P1106, P1107, P1111, P1112, P1114, P1115, P1121, and P1122 are not active.
^ The system voltage is between 10-18 volts.
^ The startup ECT is between 4-30°C (39-86°F).
^ The startup IAT is between 4-30°C (39-86°F).
^ The start up ECT and IAT are within 9°C (16°F) of each other.
^ The fuel tank level is between 20-85 percent.
^ The barometric pressure (BARO) is more than 75 kPa.
^ The vehicle speed sensor (VSS) is less than 121 km/h (75 mph).

CONDITIONS FOR SETTING THE DTC
The EVAP system can achieve vacuum but a vacuum decay is detected during the diagnostic test.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
To aid in locating intermittent leaks, use the J 41413 EVAP pressure/purge diagnostic station to pressurize the EVAP system. Move all EVAP components while testing with the J 41416 Ultrasonic Leak Detector.

TEST DESCRIPTION

Steps 1-4:

Steps 5-7:

The numbers below refer to the step numbers on the diagnostic table.
4. This step verifies that a failure condition is active.
6. This step verifies that repairs are complete and that other conditions are not present.