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Home >> Cadillac >> 1996 >> Eldorado Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0154 - Ho2S Circuit Insufficient Activity Bank 2, Sensor 1 (Front) >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Start and warm engine until coolant temperature reaches about 185°F (85°C) or greater. Using scan tool, monitor bank 2 sensor 1 voltage display for 30 seconds. If voltage remains between .3-.6 volt, go to next step. If voltage does not remain between .3-.6 volt, go to step 6).
  3. Turn ignition off. Disconnect front HO2S harness connector. Start engine. Using DVOM, check voltage between HO2S harness connector terminals "A" and "B". If voltage remains between .3-.6 volt, diagnose using DTC P0153 test. If voltage does not remain between .3-.6 volt, go to next step.
  4. Store fluid life index as indicated on scan tool. Turn ignition off for 30 seconds, then disconnect PCM connector C2. Using DVOM, check resistance between HO2S high signal circuit at PCM connector and HO2S harness connector terminal "B". If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, go to step 8).
  5. Check resistance between PCM connector C2 HO2S low signal circuit and HO2S harness connector terminal "A". If resistance is greater than 5 ohms, go to step 10). If resistance is 5 ohms or less, go to next step.
  6. Turn ignition on, with engine off. Check voltage between HO2S harness connector terminals "C" and "D". If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, go to step 8).
  7. Using jumper wire, jumper oxygen sensor terminal "D" to oxygen harness connector terminal "D". Set DVOM to amp scale. Install DVOM in series between oxygen sensor terminal "C" and harness connector terminal "D". If reading is 0.9-1.5 amps, go to step 14). If reading is not as specified, go to step 13).
  8. Check voltage between oxygen sensor harness connector terminal "D" to ground. If reading is 10.5 volts or greater, go to step 11). If reading is less than 10.5 volts, go to step 12).
  9. Repair open in HO2S high signal circuit.
  10. Repair open in HO2S low signal circuit.
  11. Repair open in HO2S ground circuit.
  12. Repair open or short to ground in HO2S ignition circuit.
  13. Replace front HO2S.
  14. Check terminal contacts at PCM connector C2. Repair as necessary. If terminal contacts are okay, go to next step.
  15. Replace PCM. Program replacement PCM using required equipment.
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