ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC P0139 O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 2)

DTC DETECTING CONDITION:

Detected when two consecutive driving cycles with fault occur.

CAUTION:

After repairing or replacing the defective part, perform the Clear Memory Mode and Inspection Mode .

WIRING DIAGRAM:

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1.CHECK ANY OTHER DTC ON DISPLAY.

Is any other DTC displayed?

Check DTC using “List of Diagnostic Trouble Code (DTC)”.

NOTE:

In this case, it is not necessary to inspect DTC P0139.

2.CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR.

1) Turn the ignition switch to OFF.

2) Disconnect the connector from ECM and rear oxygen sensor.

3) Measure the resistance of harness between ECM and rear oxygen sensor connector.

Connector & terminal

(B136) No. 21 — (E22) No. 4:

Is the resistance less than 1 Ω?

Repair the open circuit of harness between ECM and rear oxygen sensor connector.

3.CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR.

Measure the resistance between rear oxygen sensor connector and chassis ground.

Connector & terminal

(E22) No. 4 — Chassis ground:

Is the resistance 1 MΩ or more?

Repair the ground short circuit of harness.

4.CHECK REAR OXYGEN SENSOR.

Measure the resistance between the rear oxygen sensor connectors.

Terminals

No. 3 — No. 4:

Is the resistance less than 1 Ω?

Replace the rear oxygen sensor.

Temporary poor contact occurs. Check the poor contact of connector.