Signal Circuit Inspection

Ignition "OFF".
Refer to Heated Oxygen Sensor (HO2S) and disconnect Upstream O2 Sensor connector.
Ignition "ON"
Measure voltage between Pin No. 3 (V_IP) terminal of Upstream O2 Sensor harness connector and chassis ground.
Measure voltage between Pin No. 2 (V_N) terminal of Upstream O2 Sensor harness connector and chassis ground.
Measure voltage between Pin No. 1 (V_G) terminal of Upstream O2 Sensor harness connector and chassis ground.
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
Re-connect Upstream O2 Sensor connector.
Ignition "OFF".
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.
Ignition "ON" & Engine "ON".
Testing Condition: Engine Idle.
Specification: Refer to Figure below

Fig 1: Measuring Voltage Between Channels & Terminal Of Upstream O2 Sensors
Courtesy of KIA MOTORS AMERICA, INC.
Is measured value within specification?
YES
- Go to Component Inspection procedure.
NO
- Repair open or short in signal circuit between Upstream O2 Sensor and PCM and then go to "Verification Of Vehicle Repair " procedure.