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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 79 (Engine Controls - Self-Diagnostics - 4.0L) >> Diagnostic Tests >> DTC P0446: EVAP Canister Vent Blocked >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: EVAP Pressure/Purge Diagnostic Station (J-41413) is required to pressurize EVAP system in the following test.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. If DTC P0443, P0449, P0452 or P0453 is also set, repair DTC(s) before continuing with this test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If DTC P0443, P0449, P0452 or P0543 is not set, go to next step.
  3. Check for damaged EVAP canister vent valve or pinched EVAP canister vent valve hose. EVAP canister vent valve is located near fuel tank. Did you find and correct the condition? If yes, go to  15. If no, go to next step.
  4. With a scan tool, capture and record the Fail Record data and clear the DTCs. Perform the Service Bay Test using scan tool. Does the scan tool indicate that the Service Bay Test passed? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
  5. Disconnect purge line from EVAP canister purge valve. Ensure ignition is on. Using scan tool, observe fuel tank pressure parameter. If scan tool indicates fuel tank pressure is about zero in. H2O, go to next step. If scan tool does not indicate fuel tank pressure is about zero in. H2O, go to step  7.
  6. Turn ignition off. Reconnect all connectors and components. Remove fuel filler cap. Install Fuel Tank Cap Adapter (J-41415-40). Connect EVAP Pressure/Purge Station (J-41413). Install vehicle fuel filler cap to fuel fill cap adapter. Zero pressure and vacuum gauges on EVAP pressure/purge station. Turn ignition on. Using scan tool, command EVAP vent valve ON. Using EVAP pressure/purge diagnostic station, pressurize system to 5 in. H2O. Rotate EVAP pressure/purge diagnostic station rotary switch to OFF/HOLD position. Using scan tool, command EVAP vent valve OFF. Does the scan tool indicate fuel tank pressure near zero in. H2O? If yes, no problem is indicated. Fault may be intermittent. See DIAGNOSTIC AIDS . If no, go to step  8.
  7. While observing scan tool, disconnect vent hose from EVAP canister vent valve. If fuel tank pressure changes to zero in. H2O, go to step  11. If fuel tank pressure does not change to zero in. H2O, go to next step.
  8. Disconnect vent hose/pipe from EVAP canister. If fuel tank pressure changes to zero in. H2O, go to step  14. If fuel tank pressure does not change to zero in. H2O, go to step  12.
  9. Using scan tool, monitor FTP sensor voltage. If voltage is more than 4.3 volts, go to DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE . If voltage is 4.3 volts or less, go to next step.
  10. Check for poor connections at FTP sensor connector. Repair connector as necessary. After repairs, go to step  15. If connector is okay, go to step  13.
  11. Replace EVAP canister vent valve. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  15.
  12. Replace EVAP canister. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  15.
  13. Replace FTP sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  15.
  14. Repair pinched or obstructed EVAP vent hose/pipe. After repairs, go to next step.
  15. With a scan tool, capture and record the Fail Record data and clear the DTCs. Perform Service Bay Test using scan tool. Does scan tool indicate that the Service Bay Test passed? If yes, go to next step. If no, go to step  5.
  16. 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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