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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G3500, VAN PASSENGER EXTENDED, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 141 (ENGINE CONTROLS SELF-DIAGNOSTICS - 2.2L)DIAGNOSTIC TESTSDTC P0446: EVAP VENT SYSTEM PERFORMANCEDIAGNOSTIC PROCEDURES
2001 Chevrolet Chevy Express G3500, Van Passenger Extended, 6.5 F

Diagnostic Procedures

2001 Chevrolet Chevy Express G3500, Van Passenger Extended, 6.5 FSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. 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, go to next step.
  2. Check EVAP system for damaged EVAP vent valve or pinched EVAP vent hose. Did you find and correct the condition? If yes, go to step  17 . If no, go to next step.
  3. Turn ignition off. Disconnect the EVAP purge line from the EVAP purge solenoid. Turn ignition on, with engine off. Is fuel tank pressure sensor parameter within -1 to 1 in. H20? If yes, go to next step. If no, go to step  10 .
    4. NOTE: Do not exceed the specified value in this step. Exceeding specified value may produce incorrect test results.
  4. Turn ignition off. 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 Evaporative Emissions System Tester nitrogen/smoke supply hose to the Fuel Fill Cap Adapter. Turn ignition on, with engine off. Command the EVAP vent solenoid closed with a scan tool. Turn the nitrogen/smoke valve on the Evaporative Emissions System Tester control panel to NITROGEN. Use the tester's remote switch to pressurize the EVAP system to 5 in. H2O. Observe fuel tank pressure sensor parameter with a scan tool. Command the EVAP vent solenoid open with a scan tool. Is fuel tank pressure sensor parameter less than 1 in. H2O? If yes, see DIAGNOSTIC AIDS  . If no, go to next step.
  5. Using scan tool, command EVAP vent solenoid on and off. Do you hear or feel the EVAP vent solenoid click when commanded ON and OFF? If yes, go to next step. If no, go to step  8 .
  6. Disconnect the EVAP vent hose from the EVAP vent solenoid. Is the fuel tank pressure sensor parameter less than 1 in. H2O? If yes, go to step  12 . If no, go to next step.
  7. 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  14 . If no, go to step  13 .
  8. Disconnect the EVAP vent valve harness connector. Probe the EVAP vent valve control circuit with a test light connected to battery voltage. Does the test light illuminate? If yes, go to next step. If no, go to step  12 .
  9. 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  17 . If no, go to step  11 .
  10. Test for poor connections at the harness connector of the FTP. Did you find and correct the condition? If yes, go to step  17 . If no, go to step  15 .
  11. Check for poor connections at PCM harness connector. Did you find and correct the condition? If yes, go to step  17 . If no, go to step  16 .
  12. Replace EVAP vent solenoid. After replacing vent solenoid, go to step  17 .
  13. Replace EVAP canister. After replacing canister, go to step  17 .
  14. Repair blockage in EVAP vent hose. After repairs, go to step  17 .
  15. Replace FTP sensor. After replacing sensor, go to step  17 .
  16. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
    17. NOTE: Do not exceed the specified value in this step. Exceeding specified value may produce incorrect test results.
  17. Turn ignition off. Connect all disconnected components. Connect the Evaporative Emissions System Tester to the fuel fill pipe. Turn ignition on, with engine off. Command the EVAP vent solenoid closed with a scan tool. Turn the nitrogen/smoke valve on the Evaporative Emissions System Tester control panel to NITROGEN. Use the tester's remote switch to pressurize the EVAP system to 5 in. H2O. Observe the fuel tank pressure sensor parameter with a scan tool. Command the EVAP vent solenoid open with a scan tool. Is the fuel tank pressure sensor parameter less than zero in. H2O? If yes, go to next step. If no, go to step  2 .
  18. Using scan tool, observe stored information and capture information. Does the scan tool display any DTCs that you have not diagnosed? If yes, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, system is okay.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.