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Home >> Kia >> 2016 >> 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 Heated Oxygen Sensor (HO2S) 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 Figure below

    Fig 1: Measuring Voltage Between Channels & Terminal Of Upstream O2 Sensor
    G11828555Courtesy of KIA MOTORS AMERICA, INC.
  13. Is measured value within specification?

    YES 

    • Go to Component Inspection procedure below.

    NO 

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