P0140
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 voltage is unusually high during the various driving condition such as fuel-cut.
Malfunction is detected when an excessively high voltage from the sensor is sent to ECM.
Possible Cause
- Harness or connectors
(The sensor circuit is open or shorted. )
- Rear heated oxygen sensor
DTC Confirmation Procedure
CAUTION: Always drive vehicle at a safe speed.
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
1. Turn ignition switch "ON" and select "DATA MONITOR" mode with CONSULT-II.
2. Start engine and drive vehicle at a speed of more than 70 KPH (43 MPH) for 2 consecutive minutes.
3. Stop vehicle with engine running.
4. Let engine idle for 1 minute.
5. Maintain the following conditions for at least 5 consecutive seconds.
CKPS.RPM (POS) 1,300 - 3,100 rpm
VHCL SPEED SE 64 - 130 KPH (40 - 80 MPH)
B/FUEL SCHDL 0.5 - 6.4 msec
COOLAN TEMP/S 70 - 100° C (158 - 212° F)
Selector lever Suitable position
6. If 1st trip DTC is detected, go 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.
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 be below 2 V during this procedure.
5. If NG, go to "Diagnostic Procedure" below.
Wiring Diagram
EC-RRO2RH-01:
EC-RRO2RH-01 - Connector View:
RIGHT 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:
Diagnostic Procedure Step 3:
Diagnostic Procedure Step 4:
Diagnostic Procedure Step 5:
Diagnostic Procedure Step 6:
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Diagnostic Procedure Step 8:
Diagnostic Procedure Step 9:
