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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 116 (Engine Controls - Self-Diagnostics - 4.0L) >> Diagnostic Tests >> DTC P0442: EVAP System - Leak Detected >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Does the scan tool indicate DTC P0443 or DTC P0449 are also set? If yes, see DTC P0443: EVAP PURGE SOLENOID CONTROL CIRCUIT  or DTC P0449: EVAP CANISTER VENT SOLENOID CONTROL CIRCUIT  . If no, go to next step.
  3. Inspect EVAP system for the following conditions:
    • Loose, missing, or damaged service port Schrader valve.
    • Loose, incorrect, missing, or damaged fuel fill cap.
    • A damaged EVAP canister purge valve.

    Raise and support vehicle. 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  7. If no, go to next step.

  4. Using scan tool, capture and record the Fail Record data and clear DTCs. Perform the Service Bay Test using scan tool. Does scan tool indicate that the Service Bay Test passed? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
    5. NOTE: Always zero the EVAP pressure and vacuum (in. H2O) gauges on the EVAP Pressure and Purge Station before proceeding with diagnosis.
  5. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J-41415). Connect EVAP Pressure/Purge Station (J-41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, seal EVAP system. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Monitor pressure gauge for one minute. Does the EVAP system pressure remain constant? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
    6. NOTE: Always zero the EVAP pressure and vacuum (in. H2O) gauges on the EVAP Pressure and Purge Station before proceeding with diagnosis.
  6. Install the J 41415-40. Connect the J 41413 and the fuel tank cap to the fuel tank cap adapter. Turn the ignition ON, with the engine OFF. Use a scan tool to clear the DTCs from the control module. With the J 41413, continuously attempt to pressurize the EVAP system to 15 in. H2O. It may be necessary to partially lower the fuel tank to inspect components located in the upper portion of the fuel tank. With the J 41416, inspect for leaks in the following locations:
    • The EVAP system purge pipe.
    • The EVAP vapor pipe.
    • The EVAP vent hose.
    • 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 valves, permanent EVAP pipes and/or fuel tank.

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

  7. With a scan tool, capture and record the Fail Record data and clear the DTCs. Perform Service Bay Test using scan tool. Does scan tool indicate that the Service Bay Test passed? If yes, go to next step. If no, go to step  5.
  8. With a scan tool, observe the stored information, Capture Info. 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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