P0442

DTC P0442

SYSTEM DESCRIPTION

This DTC tests the evaporative emission (EVAP) system for a small leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the vacuum decay rate. At an appropriate time, the control module turns the EVAP canister purge valve ON and the EVAP vent valve ON. This allows the engine to draw a vacuum on the EVAP system. At a calibrated time, or vacuum level, the control module turns the EVAP canister purge valve OFF, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum decay. If the control module detects a leak larger than a calibrated amount, this DTC sets.




The table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent valves.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0122, P0123, P0452, P0453, P0500 are not set.
- The ignition voltage is between 11-18 volts.
- The barometric pressure (BARO) is more than 81 kPa.
- The fuel level is between 15-44 percent for a 0.040 inch leak and 44-85 percent for a 0.020 inch leak.
- The engine coolant temperature (ECT) is between 5-32°C (41-90°F).
- The intake air temperature (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 engine run time is less than 600 seconds.
- No vehicle speed DTCs are set in the transmission control module (TCM).

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) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the 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 help locate intermittent leaks, use the J 41413-200 (J 41413-100) Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the High Intensity White Light.
- To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with a High Intensity White Light.
- For intermittent conditions, refer to Intermittent Conditions. Diagnostic Strategies

TEST DESCRIPTION

Steps 1 - 4:

Steps 5 - 6:

The numbers below refer to the step numbers on the diagnostic table.
3. Introducing smoke in 15 seconds intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
5. This step verifies that repairs are complete and that no other condition is present.