P0157
Component Description
The rear heated oxygen sensor, after three way catalyst, monitors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the front heated oxygen sensor are shifted, the air fuel ratio is controlled to stoichiometric, by the signal from the rear heated oxygen sensor.
This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V. in leaner conditions.
Under normal conditions the rear heated oxygen sensor is not used for engine control operation.
CONSULT Reference Value in Data Monitor Mode
Specification data are reference values.
ECM Terminals and Reference Value
Specification data are reference values and are measured between each terminal and 32 (ECM ground).
On Board Diagnosis Logic
The rear heated oxygen sensor has a much longer switching time between rich and lean than the front heated oxygen sensor. The oxygen storage capacity before the three way catalyst causes the longer switching time. To judge the malfunctions of rear heated oxygen sensor, ECM monitors whether the minimum voltage of sensor is sufficiently low during the various driving condition such as fuel-cut.
DTC Confirmation Procedure
CAUTION: Always drive vehicle at a safe speed.
TESTING CONDITION:
Never stop engine during this test. If the engine is stopped, re-perform this test from step 2 in "Procedure for COND1".
NOTE:
- If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.
- "COMPLETED" will appear on CONSULT screen when all tests "COND1", "COND2" and "COND3" are completed.
With CONSULT
Procedure for COND1
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 "RR O2 SEN-B1 (-B2) P0137 (P0157)" of "REAR O2 SENSOR" in "DTC WORK SUPPORT" mode with CONSULT.
4. Touch "START".
5. Start engine and let it idle for at least 30 seconds.
6. Rev engine up to 2,000 rpm 2 or 3 times quickly under no load. If "COMPLETED" appears on CONSULT screen, go to step 2 in "Procedure for COND3".
If "COMPLETED" does not appear on CONSULT screen, go to the following step.
7. Drive vehicle at a speed of more than 70 kph (43 MPH) for 2 consecutive minutes.
8. When the following conditions are met, "TESTING" will be displayed at "COND1" on the CONSULT screen. Maintain the conditions continuously until "TESTING" changes to "COMPLETED" (It will take approximately 60 seconds.)
CMPS.RPM (POS) 1,300 - 3,100 rpm (A/T)
1,500 - 3,600 rpm (M/T)
Vehicle speed 64 - 130 kph (40 - 80 MPH)
0.5 - 6.4 msec (A/T)
B/FUEL SCHDL 0.5 - 5.9 msec (M/T)
Selector lever Suitable position
NOTE:
- If "TESTING" is not displayed after 5 minutes, retry from step 2 in "Procedure for COND1".
- If "COMPLETED" already appears at "COND2" on CONSULT screen before "Procedure for COND2" is conducted, it is unnecessary to conduct "Procedure for COND2".
Procedure for COND2
1. While driving, release accelerator pedal completely with "OD" OFF from the above condition (step 8) until "INCOMPLETE" at "COND2" on CONSULT screen has turned to "COMPLETED". (It will take approximately 4 seconds.)
Procedure for COND3
1. Stop vehicle and let it idle until "INCOMPLETE" of "CON D3" on CONSULT screen has turned to "COMPLETED". (It will take a maximum of approximately 6 minutes.)
2. Make sure that "OK" is displayed after touching "SELF-DIAG RESULTS". If "NG" is displayed, refer to "Diagnostic Procedure" below.
Overall Function Check
Use this procedure to check the overall function of the rear heated oxygen sensor 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 kph (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Set voltmeter probes between ECM terminal 56 (right bank sensor signal) or 57 (left bank sensor signal) and engine 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 below 0.54V 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 kph (50 MPH) in 3rd gear position (M/T), "D" position with "OD" OFF (A/T).
The voltage should be below 0.54V at least once during this procedure.
6. If NG, go to "Diagnostic Procedure" below.
EC-RRO2LH-01:
EC-RRO2LH-01 Connectors View:
Wiring Diagram LEFT BANK
Diagnostic Procedure
Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
Step 6:
Step 7:
Step 8:
Component Inspection
With CONSULT
1. Start engine and drive vehicle at a speed of more than 70 kph (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Select "FUEL INJECTION" in "ACTIVE TEST" mode, and select "RR O2 SEN-B1 (-B2)" as the monitor item with CONSULT.
4. Check "RR O2 SEN-B1 (-B2)" at idle speed when adjusting "FUEL INJECTION" to ±25%.
"RR O2 SEN-B1 (-B2)" should be above 0.56V at least once when the "FUEL INJECTION" is +25%.
"RR O2 SEN-B1 (-B2)" should be below 0.54V at least once when the "FUEL INJECTION" is -25%.
Without CONSULT
1. Start engine and drive vehicle at a speed of more than 70 kph (43 MPH) for 2 consecutive minutes.
2. Stop vehicle with engine running.
3. Set voltmeter probes between ECM terminal 56 (right bank sensor signal) or 57 (left bank sensor signal) engine 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 0.56V at least once during this procedure.
If the voltage is above 0.56V 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 kph (50 MPH) in 3rd gear position (M/T), "D" position with "OD" OFF (A/T).
The voltage should be below 0.54V at least once during this procedure.
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.