GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2007 🢒 G6 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0442

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0442: Evaporative Emissions (EVAP) System Small Leak Detected

Circuit/System Description

This diagnostic tests the evaporative emission (EVAP) system for a small leak when the key is turned OFF and the correct conditions are met. Heat from the exhaust system is transferred into a vehicle fuel tank while the vehicle is operating. When the vehicle is turned OFF and the EVAP system is sealed, a change in the fuel tank vapor temperature occurs, which results in corresponding pressure changes in the fuel tank vapor space. This change is monitored by the control module using the fuel tank pressure sensor input. The control module then makes a judgment on the integrity of the system. With a 0.51 mm (0.02 in) leak in the system, the amount of pressure change observed is significantly less than that of a sealed system.

Conditions for Running the DTC

Important: The following conditions must be met prior to ignition OFF.

    • Before the engine control module (ECM) can report DTC P0442 failed, DTCs P0446, P0455, and P0496 must run and pass.
    • DTCs P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0128, P0443, P0446, P0449, P0452, P0453, P0463, P0503, P1106, P1107, P1111, P1112, P1114, P1115, P1516, P2101, P2108, P2120, P2125, P2129, P2138, P2610 are not set.
    • The diagnostic runs once after a cold start drive cycle.
    • The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
    • The start-up engine coolant temperature (ECT) is less than 30°C (86°F).
    • The start-up IAT and ECT are within 8°C (15°F).
    • The barometric pressure (BARO) is more than 74 kPa.
    • The ambient air temperature is between 2-32°C (36-90°F).
    • The engine run time minimum is 10 minutes.
    • The vehicle has traveled more than 5 kilometers (3 miles) this trip.
    • The ECT is more than 70°C (158°F).
    • The fuel level is between 15-85 percent.
    • The ignition is OFF.
    • A refueling event is not detected.
    • DTC P0442 runs once per drive cycle when the above conditions are met.
    • One test occurs at ignition OFF after a drive cycle, and may require up to 45 minutes to complete. No more than 2 tests per day are allowed.

Conditions for Setting the DTC
    • The control module detects a pressure change that is less than a calibrated amount.
    • Several tests must be completed to report a Fail with up to 17 hours between tests.

Action Taken When the DTC Sets

DTC P0442 is a Type A DTC.

Conditions for Clearing the MIL/DTC

DTC P0442 is a Type A DTC.

Diagnostic Aids
    • To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light.
    • To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
    • A condition may exist where a leak in the EVAP system only exists under a vacuum condition. By using the scan tool Purge/Seal function to create a vacuum, seal the system and observe the FTP parameter for vacuum decay, this type of leak may be detected.

Reference Information

Schematic Reference

Evaporative Emissions Hose Routing Diagram

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Output Controls

Special Tools Required

    • J 41413-200 Evaporative Emission System Tester (EEST)
    • J 41413-VLV EVAP Port Vent Fitting Tool
    • GE-41415-50 Fuel Tank Cap Adapter
    • J 41413-300 EVAP Cap and Plug Kit
    • J 41413-SPT High Intensity White Light

Circuit/System Verification
  1. Verify the following conditions do not exist in the EVAP system:
    2. • Loose, incorrect, missing, or damaged fuel fill cap
    • Loose, missing, or damaged service port schrader valve
    • A damaged EVAP purge solenoid
    • Disconnected, incorrectly routed, kinked, or damaged EVAP pipes and hoses
    • A damaged EVAP vent valve or EVAP canister
         ⇒If you find any of the above conditions, repair as necessary.
  2. Remove the fuel fill cap. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50 .
  3. Calibrate the J 41413-200 Flow Meter to the correct leak orifice for the vehicle.
  4. Command the EVAP vent solenoid closed with a scan tool.

    5. Important: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.

  5. Activate the J 41413-200 and compare the flow meter's stable floating indicator position to the red flag. The floating indicator should be below the red flag.
    6. ⇒If the floating indicator is above the red flag, test for a leak in the EVAP system.
  6. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

Circuit/System Testing

    Important: 

       • You must start with the Circuit/System Verification before proceeding with Circuit/System Testing.
       • Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. The system flow will be less with higher temperatures.

  1. Turn the nitrogen/smoke valve on the control panel to SMOKE.
  2. Command the EVAP vent solenoid closed with a scan tool.
  3. Use the remote switch to introduce smoke into the EVAP system.
  4. Use the J 41413-VLV to open the EVAP service port. Once smoke is observed, remove the tool.

    5. Important: Introduce smoke at 15 second intervals while testing the system.

  5. Verify the entire EVAP system with the high intensity white light. Smoke should not be observed.
    6. ⇒If smoke is observed, repair the condition as necessary.
  6. Verify the EVAP system using the EVAP service port. Connect the J 41413-200 nitrogen/smoke supply hose to the EVAP service port.
  7. Command the EVAP vent solenoid closed with a scan tool.
  8. Use the remote switch to introduce smoke into the EVAP system.
  9. Verify the entire EVAP system with the high intensity white light. Smoke should not be observed.
    10. ⇒If smoke is observed, repair the condition as necessary.
  10. Verify the individual EVAP system components for a leak using the J 41413-300 . The EVAP system components should not leak.
    11. ⇒If a condition is found replace the affected component.

Repair Instructions
    •  Evaporative Emission Canister Replacement
    •  Evaporative Emission Canister Purge Solenoid Valve Replacement
    •  Evaporative Emission Canister Vent Solenoid Valve Replacement
    •  Evaporative Emission Hoses/Pipes Replacement - Chassis/Canister
    •  Fuel Tank Pressure Sensor Replacement

Repair Verification
  1. Turn the nitrogen/smoke valve to nitrogen.
  2. Command the EVAP vent valve closed with a scan tool.
  3. Use the remote switch to activate the J 41413-200 .
  4. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating indicator stabilizes.
  5. Verify the flow meter's stable floating indicator position is at or below the red flag.
  6. Clear the DTCs with a scan tool.