Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSPONTIAC2003VIBE BASE, FWD, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - SELF-DIAGNOSTICSDIAGNOSTIC TESTSDTC P0450: FUEL TANK PRESSURE SENSOR CIRCUITDIAGNOSTIC PROCEDURES
2003 Pontiac Vibe Base, FWD, Standard
Diagnostic Procedures
2003 Pontiac Vibe Base, FWD, StandardSECTION Diagnostic Procedures
- 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.
- 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.
- 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 .
- 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.
- Repair cause of trapped vapor pressure in fuel tank. After repair, go to step 14.
- 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.
- 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.
- Repair open in FTP sensor reference voltage circuit between sensor and splice SP108. After repair, go to step 14.
- 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.
- 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.
- Repair open in FTP sensor ground circuit between sensor and splice in sensor ground circuit. After repair, go to step 14.
- Replace FTP sensor. After repair, go to step 14.
- Replace PCM. After replacing PCM, go to next step.
- 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.
- 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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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.