P0139

DTC P0139: O2 Sensor Circuit Slow Response (Sensor-2)

Wiring Diagram:

Wiring Diagram




DTC Detecting Condition and Trouble Area

WARNING:
- When performing a road test, select a place where there is no traffic or possibility of a traffic accident and be very careful during testing to avoid occurrence of an accident.
- Road test should be carried out by 2 persons, a driver and a tester, on a level road.

NOTE: Check to make sure that following conditions are satisfied when using this "DTC Confirmation Procedure".
- Engine coolant temperature: 70 degrees C (158 degrees F) or more.
- The following DTCs are not detected (when DTC P0139 is detected): HO2S heater and HO2S (other than P0139).
- The following DTCs are not detected (when DTC P2A01 is detected): A/F sensor, A/F sensor heater and HO2S heater.

1. With ignition switch turned OFF, connect scan tool.
2. Turn ON ignition switch and clear DTC using scan tool.
3. Start engine and warm up to normal operating temperature.
4. Drive vehicle at 40 mph (60 km/h) or higher. (engine speed: 2500 - 3000 r/min.)
5. Keep above vehicle speed for 6 min. or more. (Throttle valve opening is kept constant in this step.)
6. Release accelerator pedal and with engine brake applied, keep vehicle coasting (with fuel cut for 5 sec. or more) and then stop vehicle.
7. Check if DTC and pending DTC exist by using scan tool. If not, check if oxygen sensor monitoring test has been completed by using scan tool. If not in both of above checks (i.e., no DTC and pending DTC and oxygen sensor monitoring test not completed), check vehicle condition (environmental) and repeat Step 3) through 6).

Step 1 - 4:

DTC Troubleshooting