GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2006 🢒 ION 🢒 Restraints 🢒 SIR 🢒 DTC P0442

DTC Descriptor

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

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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 P0443, P0449, P0452, and P0453 must run and pass.
    • DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0125, P0128, P0446, P0452, P0453, P0455, P0496, P0502, P0601, P0602, P0606, P0641, 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 between 4-30°C (39-86°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
    • 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 help locate intermittent leaks, use the J 41413-200 Evaporative Emission 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.
    • 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

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Output Controls

Special Tools Required

    • GE-41415-50 Fuel Tank Cap Adapter
    • J 41413-200 (J 41413-100) Evaporative Emission System Tester (EEST)

Circuit/System Testing

Important: 

   • Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.
   • Refer to the J 41413-200 (J 41413-100) operation manual for detailed instructions.

  1. Using the GE-41415-50 , connect the J 41413-200 (J 41413-100) to the vehicle filler neck.
  2. Use the flow meter on the J 41413-200 (J 41413-100) , calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system.
    3. ⇒If a leak is detected use the J 41413-200 (J 41413-100) to apply smoke to the EVAP system at the service port or the filler neck until the leak is located.

Repair Instructions

Important: The malfunction indicator lamp (MIL) may remain ON after the repair unless the DTCs are cleared.

    •  Evaporative Emission Canister Replacement
    •  Evaporative Emission Canister Vent Solenoid Valve Replacement
    •  Filler Tube Replacement
    •  Fuel Pump Module Replacement

Repair Verification

Use the flow meter on the J 41413-200 (J 41413-100) , calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system.