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Home >> Isuzu >> 1996 >> Hombre S >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Testing >> DTC P0140 - Ho2S Insufficient Activity Sensor 2 >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Ensure engine is at normal operating temperature. Start engine. Raise engine speed to 1200 RPM for 2 minutes. Observe HO2S voltage. If voltage is 425-456 mV, go to step 4). If voltage is not 425-456 mV, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Observe HO2S 2 voltage. If voltage is 425-456 mV, go to next step. If voltage is not 425-456 mV, go to step 11).
  4. Turn ignition on, with engine off. Disconnect HO2S 2 connector. Connect a jumper wire between ground and sensor signal circuit and ground circuit terminals at HO2S 2 harness connector. If voltage is less than 100 mV, go to next step. If voltage is 100 mV or greater, go to step 6).
  5. Turn ignition off. Check for open or poor connection at HO2S 2 harness connector. Repair as necessary. After repair is completed, go to step 11). If circuit is okay, go to step 7).
  6. Turn ignition off. Remove jumper wire and reconnect HO2S 2 connector. Disconnect PCM connector. Connect a test light between positive battery terminal and sensor ground circuit terminal at PCM harness connector. If test light is on, go to step 8). If test light is off, go to step 9).
  7. Replace oxygen sensor. After repair is completed, go to step 11).
  8. Check HO2S 2 signal circuit for open or poor connection. Repair as necessary. After repair is completed, go to step 11). If circuit is okay, go to step 10).
  9. Repair open in HO2S 2 ground circuit. After repair is completed, go to step 11).
  10. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
  11. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0140. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
  12. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.
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