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Home >> Buick >> 2002 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.1L Engine >> Diagnostic Tests >> DTC P0442: EVAP System - Leak Detected >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Does the scan tool indicate DTCs P0443, P0449, P0452, or P0453 are also set? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Inspect the Evaporative Emission (EVAP) system for the following conditions: A loose, missing, or damaged service port Schrader valve, a loose, incorrect, missing or damaged fuel fill cap, or damaged EVAP canister purge valve. Raise vehicle on a hoist. Inspect EVAP system for 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. With a scan tool, capture and record the Fail Record data and clear the DTCs. Perform the Service Bay Test. Does the scan tool indicate that the Service Bay Test passed? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
    NOTE: Always zero the EVAP pressure and vacuum (in H2O) gauges on EVAP Pressure and Purge Station before proceeding with diagnosis.
  5. Install the J-41415-40 Fuel Fill Cap Adaptor. Connect the J-41413 EVAP Pressure and Purge Station and the vehicle fuel fill cap to the J-41415-40. Turn ignition on, with engine off. Seal the EVAP system with the scan tool. Continuously pressurize the EVAP system to 15 in. H2O with the J-41413 (fuel tank may need to be partially lowered to inspect components located in upper portion of tank). Inspect for leaks in the Ultrasonic Leak Detector, the EVAP system purge pipe, vapor pipe, vent hose, fuel fill pipe/hose and fuel fill cap. Check for leaks in the fuel sender assembly and/or seal, FTP sensor seal, 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 .
  6. With a scan tool, capture and record the Fail Record data and clear the DTCs. Perform the Service Bay Test. Does the scan tool indicate that the Service Bay Test passed? If yes, go to next step. If no, repeat step  5.
  7. Using scan tool, observe stored information and Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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