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Home >> Pontiac >> 2002 >> Aztek AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0442: EVAP System - Small Leak >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Does the scan tool indicate DTC P0443, P0449, P0452 or P0453 are also set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Inspect the EVAP system for the following conditions:
    • Loose, missing, or damaged service port dust cap and/or Schrader valve.
    • Loose, incorrect, missing, or damaged fuel fill cap.
    • A damaged EVAP canister purge valve.

    Raise the vehicle on a hoist. Inspect the EVAP system for the following conditions:

    • Disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses.
    • A damaged EVAP canister vent valve or EVAP canister.

    Did you find and correct the condition? If yes, go to step  5. If no, go to next step.

    4. NOTE: The fuel tank may need to be partially lowered in order to inspect components located in the upper portion of the tank.
  4. Install the J 41415 Fuel Fill Cap Adapter. Connect the J 41413 Pressure/Purge Diagnostic Station to the fuel fill cap adapter. Turn ON the ignition, with the engine OFF. With the scan tool, seal the EVAP system. With the J 41413, continuously pressurize the EVAP system to 15 in. H2O.

    With the J 41416 Ultrasonic Leak Detector, inspect for leaks in the following locations:

    • The EVAP system purge pipe.
    • The EVAP vapor pipe.
    • The EVAP vent hose/pipe.
    • The fuel fill pipe/hose and fuel fill cap.
    • The EVAP canister.
    • The EVAP canister vent valve.
    • The EVAP canister purge valve.
    • The fuel sender assembly and/or seal.
    • The FTP sensor seal.
    • The fill limiter vent valve, pressure relief valve, rollover valve, or fuel tank.

    Did you locate and repair the system? If yes, go to next step. If no, see DIAGNOSTIC AIDS .

  5. Remove the fuel fill cap to relieve fuel tank pressure. Turn ON the ignition, with the engine OFF. Command the EVAP canister vent valve ON with a scan tool. Pressurize the EVAP system to 5 in. H2O with the J 41413. Place the control knob on the J 41413 to the OFF/HOLD position. Monitor the EVAP system pressure on the J 41413 for 5 minutes. Does the EVAP system pressure remain constant? If yes, go to next step. If no, go to step  4.
  6. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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