P0138
COMPONENT DESCRIPTION
The heated oxygen sensor 2 (rear), 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 (front) are shifted, the air fuel ratio is controlled to stoichiometric, by the signal from the heated oxygen sensor 2 (rear).
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 (rear) is not used for engine control operation.
Consult-II Reference Value In Data Monitor Mode:
ECM Terminals And Reference Value:
ON BOARD DIAGNOSIS LOGIC
The heated oxygen sensor 2 (rear) has a much longer switching time between rich and lean than the heated oxygen sensor 1 (front). The oxygen storage capacity before the three way catalyst causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2 (rear), ECM monitors whether the maximum voltage of the sensor is sufficiently high during the various driving condition such as fuel-cut.
DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
CAUTION: Always drive vehicle at a safe speed.
NOTE:
- "COMPLETED" will appear on CONSULT-II screen when all tests "COND1", "COND2" and "COND3" are completed.
- If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.
TESTING CONDITION:
Never stop engine during this test. If the engine is stopped, reperform this test from step 2.
Procedure for COND1
With Consult
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Turn ignition switch "ON" and select "HO2S2 (B1) P0138, (B2) P0158" of "HO2S2" in "DTC WORK SUPPORT" mode with CONSULT-II.
4. Touch "START".
5. Start engine (TCS switch "OFF") and let it idle for at least 30 seconds.
6. Rev engine to 2,000 rpm 2 or 3 times quickly under no load.
If "COMPLETED" appears on CONSULT-II screen, go to step 10.
If "COMPLETED" does not appear on CONSULT-II screen, go to the following step.
7. Drive vehicle at a speed of more than 70 km/h (43 MPH) for 2 consecutive minutes.
8. When the following conditions are met, "TESTING" will be displayed at "COND1" on the CONSULT-II screen. Maintain the conditions continuously until "TESTING" changes to "COMPLETED". (It will take approximately 60 seconds.)
CMPS-RPM (POS): 1,200 - 2,500 rpm
Vehicle speed: 64 - 100 km/h (40 - 62 MPH)
B/FUEL SCHDL: 0.5 - 5.0 msec
Selector lever: Suitable position
NOTE:
- If "TESTING" is not displayed after 5 minutes, retry from step 2.
- If "COMPLETED" already appears at "COND2" on CONSULT-II screen before "Procedure for COND2" is conducted, it is unnecessary to conduct step 9.
Procedure for COND2
9. While driving, release accelerator pedal completely with "OD" OFF from the above condition [step 8] until "INCOMPLETE" at "COND2" on CONSULT-II screen is turned to "COMPLETED". (It will take approximately 4 seconds.)
NOTE: If "COMPLETED" is already appears at "COND3" on CONSULT-II screen before "Procedure for COND3" is conducted, it is unnecessary to conduct step 10.
Procedure for COND3
10. Stop vehicle and let it idle until "INCOMPLETE" of "COND3" on CONSULT-II screen has turned to "COMPLETED". (It will take maximum of approximately 6 minutes.)
11. Make sure that "OK" is displayed after touching "SELF DIAG RESULTS". If "NG" is displayed, refer to "DIAGNOSTIC PROCEDURE".
OR
OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the heated oxygen sensor 2 (rear) circuit. During this check, a 1st trip DTC might not be confirmed.
Without Consult
1. Start engine and drive vehicle at a speed of more than 70 km/h (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Set voltmeter probes between ECM terminals (89) (B2), (90) (B1) (sensor signal) and ground.
4. Check the voltage when rewing engine up to 4,000 rpm under no load at least 10 times.
(depress and release accelerator pedal as soon as possible)
The voltage should be above 0.48 V at least once during this procedure.
If the voltage can be confirmed in step 4, step 5 is not necessary.
5. 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 be above 0.48 V at least once during this procedure.
6. If NG, go to "DIAGNOSTIC PROCEDURE".
EC-O2S2B1-01:
EC-O2S2B1-01 Connector View:
WIRING DIAGRAM
Super Multiple Junction (SMJ) Terminal Arrangement (B4, B101, E70, E81, F63, M3, M49, M50):
Fuse Block - Junction Block (J/B) Terminal Arrangement (B1, B2, E61, E62, E63, E64, M1):
Part 1:
Part 2:
DIAGNOSTIC PROCEDURE
COMPONENT INSPECTION
Heated oxygen sensor 2 (rear)
With Consult
1. Start engine and drive vehicle at a speed of more than 70 km/h (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Select "FUEL INJECTION" in "ACTIVE TEST" mode, and select "HO2S2 (B1) (B2)" as the monitor item with CONSULT-II.
4. Check "HO2S2 (B1) (B2)" at idle speed when adjusting "FUEL INJECTION" to ±25%.
"HO2S2 (B1) (B2)" should be above 0.48 V at least once when the "FUEL INJECTION" is +25%.
"HO2S2 (B1) (B2)" should be below 0.43 V at least once when the "FUEL INJECTION" is -25%.
OR
Without Consult
1. Start engine and drive vehicle at a speed of more than 70 km/h (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Set voltmeter probes between ECM terminals (89) (B2), (90) (B1) (sensor signal) and ground.
4. 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 be above 0.48 V at least once. If the voltage is above 0.48 V at step 4, step 5 is not necessary.
5. 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 be below 0.43 V at least once.
CAUTION:
- Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
- Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.