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DTC P0440 - EVAP System

  1. Perform On-Board Diagnostic (OBD) System Check. See BASIC TESTING article. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. If DTC P1655 or P1675 is set, diagnose affected DTCs before proceeding. If DTCs are not set, go to next step.
  3. Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays zero in. H2O, go to next step. If scan tool does not display zero in. H2O, repair faulty fuel tank pressure sensor circuit.
  4. Zero pressure and vacuum gauges on EVAP Pressure/Purge Cart (J41413). Reinstall fuel cap. Read and record FAIL RECORDS data for DTC P0440. Clear DTCs. Using scan tool, command EVAP vent solenoid ON (closed). Connect EVAP pressure/purge cart to EVAP service port. Using EVAP pressure/purge cart, attempt to pressurize EVAP system to 5 in. H2O. If specified pressure is achieved, go to next step. If specified pressure is not achieved, to step 6).
  5. Maintain EVAP system pressure at 5 in. H2O. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 5 in. H2O, go to step 8). If scan tool does not display 5 in. H2O, go to step 7).
  6. Disconnect fuel tank vapor and EVAP purge lines from EVAP canister. Plug fuel tank vapor line fitting at EVAP canister. Connect a hand vacuum pump to EVAP purge line fitting at EVAP canister. Ensure EVAP vent solenoid is still commanded ON (closed). Attempt to apply 5 in. Hg vacuum to EVAP canister. If vacuum is maintained as specified, go to step 11). If vacuum can not be maintained as specified, go to step 10).
  7. Check fuel tank vapor line and EVAP purge line for restriction. If restriction is found, repair as necessary and go to step 16). If no restriction is found, repair faulty fuel tank sensor circuit.
  8. Disconnect vacuum source line and plug vacuum source fitting at EVAP purge solenoid. Using scan tool, select and activate SYSTEM PERF. Using EVAP pressure/purge cart, pressurize EVAP system to 5 in. H2O. Observe pressure gauge on EVAP pressure/purge cart while removing plug from vacuum source fitting line at EVAP purge solenoid. If fuel tank vacuum decreases to zero in. H2O within 15 seconds, go to step 9). If vacuum does not decrease as specified, go to step 13).
  9. Connect EVAP pressure/purge cart vacuum gauge to vacuum source line. Start engine. Run engine speed to greater than 2000 RPM while observing vacuum gauge. If vacuum is greater than 15 in. Hg, check for an intermittent problem. See TESTS W/O CODES article. If vacuum is 15 in. Hg or less, go to step 14).
  10. Check if vent hose is disconnected or damaged. Check EVAP canister for damage. If a problem is found, repair as necessary and go to step 16). If no problem is found, go to step 15).
  11. Check for missing or faulty fuel cap. Check for disconnected or leaking fuel tank vapor line. Check for disconnected or damaged EVAP purge line. If a problem is found, repair as necessary and go to step 16). If no problem is found, go to next step.
  12. Using scan tool, command EVAP vent solenoid ON (closed). With EVAP pressure/purge cart connected to EVAP service port, continuously attempt to pressurize EVAP system by leaving EVAP pressure/purge cart control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J41413), locate and repair EVAP system leak. It may be necessary to lower fuel tank to check connections at top of tank. Go to step 16).
  13. Replace EVAP purge solenoid and go to step 16).
  14. Locate and repair cause of no source vacuum to EVAP purge solenoid and go to step 16).
  15. Replace EVAP vent solenoid and go to next step.
  16. Turn ignition on, engine off. Using scan tool, command EVAP vent solenoid ON (closed). Using EVAP pressure/purge cart pressurize EVAP system to 15 in. H2O. Monitor EVAP pressure/purge cart pressure gauge. Turn EVAP pressure/purge cart rotary switch to HOLD position. If pressure decreases to less than 10 in H2O within 2 minutes, return to step 3). If pressure does not decrease as specified, repair is complete.
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