P0159
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 1 V in richer conditions to 0 V in leaner conditions.
Under normal conditions the rear heated oxygen sensor is not used for engine control operation.
CONSULT-II Reference Value in Data Monitor Mode
Specification data are reference values.
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 switching response of the sensor's voltage is faster than specified during the various driving condition such as fuel-cut.
Malfunction is detected when it takes more time for the sensor to respond between rich and lean than the specified time.
Possible Cause
- Harness or connectors
(The sensor circuit is open or shorted. )
- Rear heated oxygen sensor
- Fuel pressure
- Injectors
- Intake air leaks
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.
TESTING CONDITION:
Open engine hood before conducting following procedure.
WITH CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 10 seconds.
3. Turn ignition switch "ON".
4. Select "DATA MONITOR" mode with CONSULT-II.
5. Make sure that "COOLAN TEMP/S" indicates more than 70° C (158° F).
6. Select "RR O2 SEN-B1 (-B2) P0139 (P0159)" of "REAR O2 SENSOR" in "DTC WORK SUPPORT" mode with CONSULT-II.
7. Start engine and follow the instruction of CONSULT-II.
8. Make sure that "OK" is displayed after touching "SELF-DIAG RESULTS".
If NG is displayed, refer to "Diagnostic Procedure" below.
If "CANNOT BE DIAGNOSED" is displayed, perform the following.
a. Stop engine and cool down until "COOLAN TEMP/S" indicates less than 70° C (158° F).
b. Turn ignition switch "ON".
c. Select "DATA MONITOR" mode with CONSULT-II.
d. Start engine.
e. Return to step 6 again when the "COOLAN TEMP/S" reaches to 70° C (158° F).
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.
WITH GST
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 72 (Right bank rear HO2S signal) or 71 (Left bank rear HO2S 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 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.
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 change at more than 0.06 V for 1 second during this procedure.
6. If NG, go to "Diagnostic Procedure" below.
Wiring Diagram
EC-RRO2LH-01:
EC-RRO2LH-01 - Connector View:
LEFT BANK
E87, E89, E83, B5, M17, M18, M19 Connector Views:
ECM TERMINALS AND REFERENCE VALUE MEASURED BETWEEN EACH TERMINAL AND 48.:
Diagnostic Procedure
Diagnostic Procedure Step 1:
Diagnostic Procedure Step 2:
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Diagnostic Procedure Step 9:
