P0139
DTC P0139 HO2S2
Component Description
The heated oxygen sensor 2 after three way catalyst monitors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the heated oxygen sensor 1 are shifted the air fuel ratio is controlled to stoichiometric by the signal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer conditions to 0 V in leaner conditions.
Under normal conditions the heated oxygen sensor 2 is not used for engine control operation.
CONSULT-II Reference Value In Data Monitor Mode:
On Board Diagnosis Logic
The heated oxygen sensor 2 has a much longer switching time between rich and lean than the heated oxygen sensor 1. The oxygen storage capacity before the three way catalyst causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2 ECM monitors whether the switching response of the sensor 5 voltage is faster than specified during the various driving condition such as fuel-cut.
DTC Confirmation Procedure
NOTE: If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.
WITH CONSULT-II
TESTING CONDITION:
- Open engine hood before conducting following procedure.
- For the best results, perform "DTC WORK SUPPORT" at a temperature of 0 to 30 °C (32 to 86 °F).
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Select �HO2S2 (B1) P0139" or "HO2S2 (B2) P0159" of "HO2S2" in "DTC WORK SUPPORT" mode with CONSULT-II.
6. Follow the instruction of CONSULT-II.
7. Make sure that "OK" is displayed after touching "SELF-DIAG RESULTS".
If NG is displayed, refer to "Diagnostic Procedure". If "CANNOT BE DIAGNOSED" is displayed, perform the following.
a. Turn ignition switch "OFF" and leave the vehicle in a cool place (soak the vehicle).
b. Turn ignition switch "ON" and select "COOLAN TEMP/S" in DATA MONITOR" mode with CONSULT-II.
c. Start engine and warm it up while monitoring "COOLAN TEMP/S" indication on CONSULT-II.
d. When "COOLAN TEMP/S" indication reaches to 70 °C (158 °F), go to step 3.
Overall Function Check
Use this procedure to check the overall function of the heated oxygen sensor 2 circuit. During this check, a DTC might not be confirmed.
WITH GST
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF" and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Set voltmeter probes between ECM terminal 88 (HO2S2 bank 1 signal) or 90 (HO2S2 bank 2 signal) and engine ground.
6. Check the voltage when racing up to 4,000 rpm under no load at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
The voltage should change at more than 0.06 V for 1 second during this procedure.
If the voltage can be confirmed in step 4, step 5 is not necessary.
7. Keep vehicle at idling for 10 minutes, then check the voltage. Or check the voltage when coasting from 80 km/h (50 MPH) in "D" position with "OD" OFF.
The voltage should change at more than 0.06 V for 1 second during this procedure.
8. If NG, go to "Diagnostic Procedure".
EC-O2S2B1-01:
EC-O2S2B2-01:
Wiring Diagram
Diagnostic Procedure (Steps 1 - 2):
Diagnostic Procedure (Steps 3 - 4):
Diagnostic Procedure (Steps 5 - 6):
Diagnostic Procedure (Steps 7 - 9):
Diagnostic Procedure