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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P0442: EVAP System - Small Leak >> Diagnostic Procedures

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 or DTC P0449 are also set? If yes, see DTC P0443: EVAP PURGE SOLENOID CONTROL CIRCUIT  or DTC P0449: EVAP VENT VALVE PERFORMANCE  . 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  6. If no, go to next step.

  4. With a scan tool, clear the DTCs. Perform the Service Bay Test. See INSPECTION/MAINTENANCE EVAPORATIVE EMISSION SYSTEM SET PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Does the scan tool indicate that the Service Bay Test passed? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
    5. NOTE: The fuel tank may need to be partially lowered in order to inspect components located in the upper portion of the tank.
  5. With the J 41413 EVAP Pressure/Purge Diagnostic Station, 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 .

  6. Perform the Service Bay Test. See INSPECTION/MAINTENANCE EVAPORATIVE EMISSION SYSTEM SET PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Does the scan tool indicate that the Service Bay Test passed? If yes, go to next step. If no, go to step  2.
  7. 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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