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Home >> Pontiac >> 2003 >> Vibe Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Self-Diagnostics >> Diagnostic Tests >> DTC P0450: Fuel Tank Pressure Sensor Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Loosen fuel tank filler cap to release any pressure inside fuel tank. Turn ignition switch to RUN position, engine OFF. Observe Fuel Tank Pressure (FTP) sensor parameter on scan tool. Is FTP sensor 0.0-0.5 in. H2O? If yes, go to next step. If no, go to step  4.
  3. Use scan tool to clear DTCs. Place vehicle into CHECK MODE using scan tool. See SERVICE BAY TESTS  under SELF-DIAGNOSTIC SYSTEM. Operate vehicle within freeze frame conditions as noted. Does DTC P0450 set? If yes, go to step  6. If no, go to DIAGNOSTIC AIDS .
  4. Remove FTP sensor. Connect FTP sensor harness connector. Turn ignition switch to RUN position, engine OFF. Observe FTP sensor parameter on scan tool. Is FTP sensor 0.0-0.5 in. H2O? If yes, go to next step. If no, go to step  6.
  5. Repair cause of trapped vapor pressure in fuel tank. After repair, go to step  14.
  6. Turn ignition OFF. Disconnect FTP sensor 3-pin harness connector. Turn ignition switch to RUN position, engine OFF. Use DMM to measure reference circuit voltage on harness side of FTP sensor connector. Does voltage equal 5.0 volts? If yes, go to next step. If no, go to step  8.
  7. Measure voltage from FTP sensor input circuit on harness side using a DMM. Is voltage near 4.9 volts? If yes, go to step  10. If no, go to step  9.
  8. Repair open in FTP sensor reference voltage circuit between sensor and splice SP108. After repair, go to step  14.
  9. Check FTP sensor input circuit for an open or a short. Verify input circuit is not shorted to sensor ground circuit. Repair as necessary. Was a repair necessary? If yes, go to step  14. If no, go to step  13.
  10. Probe FTP sensor ground circuit on harness side with a test light connected to battery voltage. Does test light illuminate? If yes, go to step  12. If no, go to next step.
  11. Repair open in FTP sensor ground circuit between sensor and splice in sensor ground circuit. After repair, go to step  14.
  12. Replace FTP sensor. After repair, go to step  14.
  13. Replace PCM. After replacing PCM, go to next step.
  14. Use scan tool to clear DTCs. Turn ignition OFF for 30 seconds. Start engine. Operate vehicle within CONDITIONS FOR RUNNING DTC  or until EVAP test is complete. Does DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. Using scan tool, observe stored information, CAPTURE INFO. Does scan tool display any DTCs that have not been diagnosed? If yes, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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