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Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Pontiac Sunfire, 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  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 that DTCs P0452 or P0453 also set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Inspect EVAP system for damaged EVAP vent valve or pinched EVAP vent hose. Did you find and correct the condition? If yes, go to step  19. If no, go to next step.
  4. Install Fuel Tank Cap Adapter (J-41415-40) to fuel filler neck. Install EVAP Pressure/Purge Diagnostic Station (J-41413) and fuel tank cap to adapter. Turn ignition on, engine off. Command EVAP vent valve on (closed) using scan tool. Using EVAP pressure/purge diagnostic station, pressurize EVAP system to 13 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Using scan tool, compare Fuel Tank Pressure (FTP) sensor value to EVAP pressure/purge diagnostic station gauge value. Are the EVAP pressure/purge diagnostic station gauge and the scan tool FTP sensor values similar? If yes, go to next step. If no, go to step  9.
  5. Monitor the J-41413 gauge. Command the EVAP canister vent valve OFF. Did the EVAP pressure/purge diagnostic station gauge drop quickly to about 0 in. H2O? If yes, refer to INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
  6. Command EVAP vent valve on and off using scan tool. EVAP vent valve is located near fuel tank under vehicle. Do you hear or feel the EVAP vent valve click when commanded ON and OFF? If yes, go to next step. If no, go to step  10.
  7. Disconnect EVAP vent hose from the EVAP canister vent valve. Did the EVAP pressure/purge diagnostic station gauge drop quickly to about 0 in. H2O? If yes, go to step  14. If no, go to next step.
  8. Disconnect EVAP vent hose from EVAP canister. Did the EVAP pressure/purge diagnostic station gauge drop quickly to about zero in. H2O? If yes, go to step  16. If no, go to step  15.
  9. Is FTP sensor value is more than 4.3 volts? If yes, go to DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE . If no, go to step  12.
  10. Disconnect EVAP vent valve harness connector. Probe the EVAP canister vent valve control circuit with a test light connected to a B+. Does the test light illuminate? If yes, go to next step. If no, go to step  14.
  11. Test the control circuit of the EVAP vent valve for a short to ground. Did you find and correct the condition? If yes, go to step  19. If no, go to step  13.
  12. Check Fuel Tank Pressure (FTP) sensor connector for poor connections. Did you find and correct the condition? If yes, go to step  19. If no, go to step  17.
  13. Test for poor connections at the harness connector of the control module. Did you find and correct the condition? If yes, go to step  19. If no, go to step  18.
  14. Replace EVAP vent valve. When complete, go to step  19.
  15. Replace EVAP canister. When complete, go to step  19.
  16. Repair blockage in EVAP vent hose. After repairs, go to step  19.
  17. Replace FTP sensor. When complete, go to step  19.
  18. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing PCM, go to next step.
  19. Reconnect all EVAP hardware that was previously disconnected. Turn ignition on, engine off. Command EVAP canister vent valve on (closed) using scan tool. Using EVAP pressure/purge diagnostic station, pressurize EVAP system to 13 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Command EVAP canister vent valve off (open). If EVAP pressure/purge diagnostic station value is near zero in. H2O, go to next step. If EVAP pressure/purge diagnostic station value is not near zero in. H2O, go to step  3.
  20. With a scan tool, observe the stored information, Capture Info. 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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