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Home >> Isuzu >> 1997 >> Rodeo LS, 2.6 E >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 2.6L >> Circuit Testing >> DTC P0140 - Ho2S Insufficient Activity Sensor 2 >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. See BASIC TESTING article. Go to next step.
  2. Start engine and allow it to reach operating temperature. Place gear selector in Park or Neutral. Apply parking brake. Increase engine speed to greater than 1200 RPM for 2 minutes. Using scan tool, read HO2S 2 voltage. If voltage is not switching from greater than 0.475 volt to less than 0.425 volt, go to next step. If voltage is as specified, go to step 4).
  3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC P0140 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0140 FAILED THIS IGN, see DIAGNOSTIC AIDS  .
  4. Check for faulty connection at HO2S 2. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to next step.
  5. With ignition off, check for faulty connection at PCM. If faulty connection is found, repair as necessary. Retest system. If connection is okay, go to next step.
  6. Turn ignition off. Disconnect PCM connectors. Check resistance of HO2S 2 harness connector signal circuit. If resistance is greater than 5 ohms, repair open or faulty connection as necessary. Retest system. If resistance is 5 ohms or less, go to next step.
  7. Reconnect PCM harness. Turn ignition on. Using DVOM, check voltage between HO2S 2 harness connector signal and heater ground circuits. If voltage is about 3-4 volts, go to step 9). If voltage is not as specified, go to next step.
  8. Check both signal circuits for a short to ground or voltage. Repair as necessary. Retest system. If no short exists, go to step 11).
  9. Disconnect HO2S 2 harness connector. Connect a jumper wire between HO2S 2 harness connector signal and ground circuits, and heater ground. If voltage is 0-.01 volt, go to next step. If voltage not 0-.01 volt, go to step 11).
  10. Replace HO2S 2. Retest system.
  11. Replace PCM. Program replacement PCM using required equipment. Retest system.
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