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Home >> Chevrolet >> 2001 >> Cavalier LS, 2.2 4 >> Repair and Diagnosis >> External Pages >> Different car >> Section 36 (Engine Controls Self-Diagnostics - 2.4L) >> Diagnostic Tests >> DTC P0446: EVAP Canister Vent Blocked >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Pontiac Sunfire 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. Did DTCs P0452 or P0453 also set? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, go to next step.
  3. Inspect the EVAP system for a damaged EVAP vent valve, or a 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 the J-41415-40 Fuel Tank Cap Adaptor to the fuel filler neck. Install the J-41413 EVAP Pressure/Purge Diagnostic Station and the fuel tank cap to the adapter. Turn ignition on, with engine off. Command the EVAP vent valve ON (closed) with a scan tool. With the J-41413, pressurize the EVAP system to 13 in. H2O. Rotate the J-41413 rotary switch to the OFF/HOLD position. Using the scan tool compare the Fuel Tank Pressure (FTP) sensor value to the J-41413 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 EVAP pressure/purge diagnostic station gauge. Command the EVAP canister vent valve OFF (open). 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 the EVAP vent valve ON and OFF with a scan tool. 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. Turn ignition off. Reconnect all previously disconnected hardware. With a scan tool, command the EVAP vent valve ON. With the J-41413, pressurize the EVAP system to 13 in. H2O. Rotate the J-41413 rotary switch to the OFF/HOLD position. Disconnect the EVAP vent hose from the EVAP vent valve. Does the scan tool indicate FTP about 0 in. H2O. If no, go to step  14 . If no, go to next step.
  8. Disconnect the EVAP vent hose from the EVAP canister. Does the scan tool indicate FTP about 0 in. H2O? If yes, go to step  16 . If no, go to step  15 .
  9. Does the scan tool indicate FTP sensor voltage more than 4.3 V? If yes, go to DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE  . If no, go to step  12 .
  10. Disconnect the EVAP vent valve harness connector. Probe the EVAP 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. Test for poor connections at the harness connector of the FTP. 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 PCM. Did you find and correct the condition? If yes, go to step  19 . If no, go to step  18 .
  14. Replace EVAP canister vent valve. After repairs, go to step  19 .
  15. Replace EVAP canister vent valve. After repairs, go to step  19 .
  16. Repair blockage in EVAP vent hose. After repairs, go to step  19 .
  17. Replace FTP sensor. After repairs, go to step  19 .
  18. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  19. Reconnect all of the EVAP hardware that was previously disconnected. Turn ignition on, with engine off. Command the EVAP canister vent valve ON (closed) with a scan tool. With the J-41413 pressurize the EVAP system to 13 in. H2O. Rotate the J-41413 rotary switch to the OFF/HOLD position. Command the EVAP canister vent valve OFF (open). Is the EVAP pressure/purge diagnostic station value about 0 in. H2O? If yes, go to next step. If no, go to step  3 .
  20. Using scan tool, observe stored information and Capture Info. If scan tool displays any undiagnosed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no other DTCs are displayed, system is okay.
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