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Home >> Isuzu >> 2000 >> Trooper S, 4WD, Part Time >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 3.2L & 3.5L >> Diagnostic Trouble Code Identification >> DTC P0442: EVAP System Small Leak Detected >> Diagnostic Procedure
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Diagnostic Procedure

  1. Perform On-Board Diagnostic (OBD) System Check. See BASIC DIAGNOSTIC PROCEDURES article. Go to next step.
  2. Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 1.51 volts, go to next step. If scan tool display is not as specified, go to DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE  or DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE  .
  3. Zero pressure and vacuum gauges on EVAP Pressure/Purge Cart (J41413). Reinstall fuel cap. Read and record FAIL RECORDS data for DTC P0442. Clear DTCs. Connect EVAP pressure/purge cart to EVAP service port. Using scan tool, command EVAP vent solenoid ON (closed). Using EVAP pressure/purge cart, pressurize EVAP system until FUEL TANK PRESSURE reading is 1.47 volts (1.52-1.69 volts on VehiCROSS). If specified FUEL TANK PRESSURE reading is achieved, go to next step. If specified pressure is not achieved, go to DTC P0452: FUEL TANK PRESSURE SENSOR LOW VOLTAGE  or DTC P0453: FUEL TANK PRESSURE SENSOR HIGH VOLTAGE  .
  4. Start engine and allow to idle. Using scan tool, command EVAP vent solenoid ON (closed). Using EVAP pressure/purge cart pressurize EVAP system to 15 in. H2 O. Monitor EVAP pressure/purge cart pressure gauge. Turn EVAP pressure/purge cart rotary switch to HOLD position. If FUEL TANK PRESSURE reading drops below 1.47-1.51 volts within 2 minutes, go to next step. If pressure does not decrease as specified, check for an intermittent problem. See DIAGNOSTIC AIDS .
  5. 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 vacuum to EVAP canister until FUEL TANK PRESSURE reading reaches 1.46 volts (or vacuum gauge reads 5.0 in. Hg on VehiCROSS). If vacuum is maintained at specified level, go to step  8. If vacuum can not be maintained as specified, go to next step.
  6. 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  10. If no problem is found, go to next step.
  7. Replace EVAP vent solenoid and go to step  10.
  8. 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  10. If no problem is found, go to next step.
  9. Using scan tool, command EVAP vent solenoid ON (closed). With EVAP pressure/purge cart connected to EVAP service port, attempt to pressurize EVAP system by leaving EVAP pressure/purge cart control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J41416), locate and repair EVAP system leak. It may be necessary to lower fuel tank to check connections at top of tank. Go to next step.
  10. 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. H2 O. Monitor EVAP pressure/purge cart pressure gauge. Turn EVAP pressure/purge cart rotary switch to HOLD position. If FUEL TANK PRESSURE reading drops to less than 2.14 volts within 2 minutes, return to step  2. If pressure does not decrease as specified, repair is complete.
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