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Home >> Buick >> 2001 >> Regal LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P0442: EVAP System Small Leak Detected >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
  2. If scan tool indicates DTCs P0443, P0449, P0452, P0453, or P1441 are also set, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not indicate DTCs P0443, P0449, P0452, P0453, or P1441 are also set, go to next step.
  3. Inspect 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.
    • Damaged EVAP canister purge valve.
    • Disconnected, improperly routed, kinked, or damaged EVAP pipes and hose.
    • Damaged EVAP canister vent valve or EVAP canister.

    If problem was found, repair as necessary. After repairs, go to step  5. If problem was not found, go to next step.

    4. NOTE: Always zero EVAP pressure and vacuum (in. H2O) gauges on EVAP pressure and purge station before proceeding with diagnosis.
    NOTE: Fuel tank may need to be partially lowered to inspect components located in upper portion of tank.
  4. Install Fuel Tank Cap Adapter (J 41415-40). Connect EVAP Pressure and Purge Station (J 41413) to fuel tank cap adapter. Turn ignition on, engine off. Using scan tool, seal EVAP system. Using EVAP pressure and purge station, continuously pressurize EVAP system to 15 in. H2O. Using Ultrasonic Leak Detector (J 41416), inspect for leaks in the following locations:
    • EVAP system purge pipe.
    • EVAP vapor pipe.
    • EVAP vent hose.
    • Fuel fill pipe/hose and fuel fill cap.
    • EVAP canister.
    • EVAP canister vent valve.
    • EVAP canister purge valve.
    • Fuel sender assembly and/or seal.
    • Fuel Tank Pressure (FTP) sensor seal.
    • Fill limiter vent valve, pressure relief valve, rollover valve, or fuel tank.

    If problem was found, repair as necessary. After repairs, go to next step. If problem was not found, see DIAGNOSTIC AIDS .

  5. Remove fuel fill cap for 30 seconds to relieve fuel tank pressure. Reinstall fuel fill cap. Turn ignition on, engine off. Using scan tool, command EVAP canister vent valve on. Using EVAP pressure and purge station, pressurize EVAP system to 5 in. H2O. Place control knob on EVAP pressure and purge station to OFF/HOLD position. Monitor EVAP system pressure on EVAP pressure and purge station for 5 minutes. If EVAP system pressure remains constant, go to next step. If EVAP system pressure does not remain constant, go to step  4.
  6. Using scan tool, observe stored information. If scan tool displays any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any DTCs, system is okay.
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