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Home › Kia › 2015 › Optima Hybrid › Repair and Diagnosis › Engine Performance › System › Engine Control System Diagnosis (3 Of 3) (HEV) › DTC P2251: O2 Sensor Reference Ground Circuit Open-Bank 1 Sensor 1 › Wiring Inspection › Signal Circuit Inspection

Signal Circuit Inspection

  1. Ignition "OFF".
  2. Refer to EXHAUST MANIFOLD and disconnect Upstream O2 Sensor connector.
  3. Ignition "ON"
  4. Measure voltage between Pin No. 3 (V_IP) terminal of Upstream O2 Sensor harness connector and chassis ground.
  5. Measure voltage between Pin No. 2 (V_N) terminal of Upstream O2 Sensor harness connector and chassis ground.
  6. Measure voltage between Pin No. 1 (V_G) terminal of Upstream O2 Sensor harness connector and chassis ground.
  7. Measure voltage between Pin No. 6 (V_RC) terminal of Upstream O2 Sensor harness connector and chassis ground.

    Specification :  Pin No. 3 (V_IP) : 2.6V / Pin No. 2 (V_N) : 2.1V / Pin No. 1 (V_G) : 2.1V / Pin No. 6 (V_G) : 2.6V

  8. Re-connect Upstream O2 Sensor connector.
  9. Ignition "OFF".
  10. Connect VMI to GDS and set up an oscilloscope as follow (2-channel);

    Channel A (+) : Pin No. 6 (V_RC) terminal of Upstream O2 Sensor.

    Channel A (-) : Pin No. 1 (V_G) terminal of Upstream O2 Sensor.

    Channel B (+) : Pin No. 3 (V_IP) terminal of Upstream O2 Sensor.

    Channel B (-) : Pin No. 2 (V_N) terminal of Upstream O2 Sensor.

  11. Ignition "ON" & Engine "ON".
  12. Testing Condition : Engine Idle.

    Specification :  Refer to illustration

    Fig 1: Signal Circuit Related Waveforms
    G00552101Courtesy of KIA MOTORS AMERICA, INC.
  13. Is measured value within specification?

    YES 

    NO 

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