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Home >> Pontiac >> 2003 >> Aztek FWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0446: EVAP Vent Valve Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Observe the Freeze Frame/Failure Records for this DTC. Perform the Service Bay Test with scan tool. Does the scan tool indicate that the Service Bay Test passed? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
  3. Inspect the EVAP system for a damaged EVAP vent valve or pinched EVAP vent hose. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  4. Disconnect the purge line from the EVAP purge valve. Turn ignition on, with engine off. With scan tool, observe the FTP parameter. Does the scan tool indicate FTP is 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 off. Reconnect all previously disconnected hardware. Install the Fuel Fill Cap Adapter (J-41415-40). Connect the EVAP Pressure/Purge Diagnostic Station (J-41413) and the vehicle fuel fill cap to the Fuel Fill Cap Adapter. Turn ignition on, with engine off. With a scan tool, seal the EVAP system. With the EVAP Pressure/Purge Diagnostic Station, pressurize the EVAP system to 5 in. H2O. Rotate the rotary switch to the OFF/HOLD position. Command the EVAP canister vent valve OFF with a scan tool. Does the scan tool indicate FTP near zero in.H2O? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
  6. Disconnect the EVAP vent pipe from the EVAP canister. Does the scan tool indicate fuel tank pressure at 1 in. H2O? If yes, go to step  11. If no, go to next step.
  7. Disconnect the EVAP vent pipe from the EVAP canister. Does the scan tool indicate FTP 1 in. H2O? If yes, go to next step. If no, go to step  12.
  8. Repair pinched or restricted EVAP vent hose. After repairs, go to step  13.
  9. Test for an intermittent and for a poor connection at the control module. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  10. Replace FTP sensor. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. After repairs, go to step  13.
  11. Replace EVAP vent valve. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. After repairs, go to step  13.
  12. Replace EVAP canister. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. After repairs, go to next step.
  13. Perform the Service Bay Test with scan tool. Does the scan tool indicate that the Service Bay Test passed? If yes, go to next step. If no, go to step  3.
  14. Observe the stored information, Capture Info with a scan tool. 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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