LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Kia >> 2019 >> Optima EX >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System Diagnosis (5 Of 6) (PHEV) >> DTC P2251-00: O2 Sensor Reference Ground Circuit/Open (Bank 1 Sensor 1) >> Wiring Inspection >> Signal Circuit Inspection
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Signal Circuit Inspection

  1. Ignition "OFF".
  2. Disconnect Battery (-) terminal.
  3. Refer to ENGINE CONTROL MODULE (ECM) "service information" and disconnect ECM/PCM connector.
  4. Measure resistance between Pin No. 6 (V_IP) terminal of Upstream O2 Sensor connector and Pin No. 83 (V_IP) terminal of ECM/PCM harness connector.
  5. Measure resistance between Pin No. 1 (V_N) terminal of Upstream O2 Sensor connector and Pin No. 105 (V_N) terminal of ECM/PCM harness connector.
  6. Measure resistance between Pin No. 3 (V_G) terminal of Upstream O2 Sensor connector and Pin No. 84 (V_G) terminal of ECM/PCM harness connector.
  7. Measure resistance between Pin No. 4 (V_RC) terminal of Upstream O2 Sensor connector and Pin No. 104 (V_RC) terminal of ECM/PCM harness connector.

    Specification:  Approx. below 1Ω

  8. Is the measured value within specification?

    YES 

    NO 

    • Repair open or short in signal circuit between Upstream O2 Sensor and ECM/PCM and then go to "VERIFICATION OF REPAIR " procedure.
scientia non olet · About LEMON Manuals