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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 107 (Engine Controls - Self-Diagnostics - 3.5L) >> Diagnostic Tests >> DTC P0446: EVAP Canister Vent Blocked >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 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 P0543 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. If any problems are found, repair as necessary. After repairs, go to  15. If no problems are found, 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  9.
  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. If fuel tank pressure changes to zero in. H2O, no problem is indicated. Fault may be intermittent. See DIAGNOSTIC AIDS . If fuel tank pressure does not change to zero in. H2O, 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. After repairs, go to step  15.
  12. Replace EVAP canister. After repairs, go to step  15.
  13. Replace FTP sensor. FTP sensor is located on top of fuel tank and can be accessed through an inspection panel in trunk. 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. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, system is okay. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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