P0442
Diagnostic Chart (Part 1 Of 3):
Diagnostic Chart (Part 2 Of 3):
Diagnostic Chart (Part 3 Of 3):
Schematic:
CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) tests the Evaporative Emission (EVAP) system for the following conditions:
^ Large and small leaks
^ Excess vacuum
^ Purge flow during non-commanded conditions
^ Fuel level and fuel pressure sensor faults
^ EVAP purge and vent valve faults
The PCM monitors the fuel tank pressure sensor in order to determine the level of vacuum or pressure in the EVAP system. The PCM commands both the EVAP purge solenoid and the EVAP vent valve ON when the Conditions for Running the DTC are met in order to apply an engine vacuum to the EVAP system. The PCM commands the EVAP purge solenoid OFF once the system has reached a predetermined level of vacuum. The EVAP system should HOLD the vacuum in the sealed system. The PCM sets this DTC in order to indicate a small leak if the EVAP system fails to hold a predetermined level of vacuum for a predetermined length of time. This DTC sets after failing the above test twice.
CONDITIONS FOR RUNNING THE DTC
^ No active Manifold Absolute Pressure (MAP) DTCs
^ No active Intake Air Temperature (IAT) DTCs
^ No active Throttle Position (TP) DTCs
^ No active Heated Oxygen Sensor (HO2S) DTCs
^ No active Vehicle Speed Sensor (VSS) DTCs
^ No active system voltage DTCs
^ The barometric pressure is more than 75 kpa.
^ The fuel level is between 15-85 percent of full capacity.
^ The TP sensor angle is less than 75 percent.
^ The vehicle speed is less than 102 km/h (65 mph).
^ The Engine Coolant Temperature (ECT) is between 4°C (39°F) and 30°C (86°F).
^ The Intake Air Temperature (IAT) is between 4°C (39°F) and 30°C (86°F).
^ The start up ECT and IAT are within 9°C (16°F) of each other.
CONDITIONS FOR SETTING THE DTC
The vacuum in the EVAP system decays or leaks at too fast a rate.
IMPORTANT: This DTC does NOT report a first failed test. A first fail of this DTC will have a scan tool status as Not Run. Use the scan tool data display parameter of EVAP test result to determine if this DTC has failed or passed for this ignition cycle.
ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the DTC.
DIAGNOSTIC AIDS
IMPORTANT:
^ Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
^ An accurate indication of fuel level is required for the PCM to properly pass or fail this DTC. Always diagnose fuel level sensor DTCs before performing this DTCs diagnostic table. Always inspect for fuel level sensor DTCs stored as History.
^ The Service Bay Test may have to be performed in cold ambient air temperatures when the vehicle is running a winter grade fuel. The scan tool displays a message when the service bay test does not run.
^ Inspect for charcoal release from the vapor canister. Refer to the Evaporative Emission (EVAP) System Cleaning procedure.
CONDITIONS FOR RUNNING THE SERVICE BAY TEST
^ The battery voltage is between 10.5 volts and 17.5 volts.
^ The fuel level is between 15-85 percent of the full capacity.
^ The engine temperature is between 3.5°C (38°F) and 35°C (95°F).
Perform a physical inspection of the EVAP system.
Inspect for the following conditions:
^ A loose, missing, defective, or incorrect fuel tank cap
^ Incorrectly routed or defective EVAP system vacuum and vapor lines
^ A malfunctioning or damaged vapor canister
^ Charcoal release from the vapor canister-Refer to Evaporative Emission (EVAP) System Cleaning.
The vacuum and pressure in the EVAP system is measured in inches of Water (H2O). Most gauges measure vacuum in inches of Mercury (Hg) and pressure in pounds Per Square Inch (psi). The following shows how the values compare:
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. You may need to partially lower the fuel tank in order to inspect the upper portion of the tank and the EVAP line connections.
4. An intermittent leak or restriction is indicated if the vehicle passes the Service Bay Test. A fuel tank cap that is loose or off causes this DTC to set.
If the Service Bay Test cannot be run, proceed to step 5. If a fault is not currently present, the diagnostic table steps will return you to step 3.
12. This step tests for a leak at the top of the fuel tank, at the fuel filler hose, and the fuel cap. Place the ultrasonic leak detector in these areas. Refer to the information supplied with the EVAP pressure and purge diagnostic cart on proper setup and adjustment procedures.
13. Tests for restrictions in EVAP system.
19. A fuel tank pressure sensor that does not correctly respond to pressure, or vacuum, causes this DTC to set.