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Home >> Saturn >> 2003 >> Ion 1 Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0446: Evaporative Emission Control System Vent Control Circuit >> 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. Is DTC P0447 set? If yes, go to DTC P0447: EVAP VENT VALVE CONTROL CIRCUIT OPEN . If no, go to next step.
  3. Inspect the EVAP system for the following conditions:
    • A damaged EVAP vent solenoid.
    • A pinched EVAP vent hose.
    • A damaged EVAP canister.

    Did you find and correct the condition? If yes, go to step  14. If no, go to next step.

  4. Turn OFF the ignition. Remove the fuel filler cap. Turn ignition on, with engine off. Is the Fuel Tank Pressure Sensor parameter within -1 to 1 in. H2O? If yes, go to next step. If no, go to step  9.
    5. NOTE: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  5. Turn ignition switch to OFF position. Connect the EVAP purge pipe. Connect the Evaporative Emissions System Tester (J 41413-200) power supply clips to a known-good 12-volt source. Install the Fuel Fill Cap Adapter (J 41415-40) to the fuel fill pipe. Connect the fuel fill cap to the fuel fill cap adapter. Connect the EEST nitrogen/smoke supply hose to the fuel fill cap adapter. Turn ignition switch to RUN position, engine OFF. Command the EVAP vent solenoid closed using a scan tool. Turn the nitrogen/smoke valve on the EEST control panel to NITROGEN. Use the remote switch to pressurize the EVAP system to 5 in. H2O. Observe the FTP sensor parameter using a scan tool. Command the EVAP vent solenoid open. Is the FTP Sensor parameter less than 1 in. H2O? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  6. Command the EVAP vent solenoid open with a scan tool. Is the Fuel Tank Pressure Sensor parameter less than 1 in. H2O? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  7. Remove the EVAP canister vent solenoid from the EVAP canister. Is the Fuel Tank Pressure Sensor parameter less than 1 in. H2O? If yes, go to step  11. If no, go to next step.
  8. Disconnect the EVAP vent hose from the EVAP canister. Is the Fuel Tank Pressure Sensor parameter less than 1 in. H2O? If yes, go to step  12. If no, go to step  10.
  9. Check for an intermittent and for a poor connection at the FTP sensor. Did you find and correct the condition? If yes, go to  14. If no, go to step  13.
  10. Repair pinched or restricted EVAP vent hose. After repair, go to step  14.
  11. Replace EVAP vent solenoid. See EVAP CANISTER VENT SOLENOID under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL & INSTALLATION - ION article. After replacement, go to step  14.
  12. Replace EVAP canister. See EVAP CANISTER under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL & INSTALLATION - ION article. After replacement, go to step  14.
  13. Replace FTP sensor. See FUEL TANK PRESSURE SENSOR under SENSORS & SWITCHES in REMOVAL & INSTALLATION - ION article. After replacement, go to next step.
    14. NOTE: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  14. Turn ignition switch to RUN position. Connect all disconnected components. Connect the EEST to the fuel fill pipe. Turn ignition switch to RUN position, engine OFF. Command the EVAP vent solenoid closed using a scan tool. Turn the nitrogen/smoke valve on the EEST control panel to NITROGEN. Use the remote switch to pressurize the EVAP system to 5 in. H2O. Observe the FUEL TANK PRESSURE SENSOR parameter using a scan tool. Command the EVAP vent solenoid open using a scan tool. Is the FTP sensor parameter less than zero in. H2O? If yes, go to next step. If no, go to step  3.
  15. Using a scan tool, observe the 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 at this time.
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