P0136

COMP0NENT DESCRIPTION
The rear heated oxygen sensor (Rear HO2S), after three way catalyst, monitors the oxygen level in the exhaust gas.
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 electrical resistance of ceramic zirconia drastically changes at the ideal air-fuel ratio.
The output voltage of the sensor, depending on its resistance, is approximately 0 to 1.0V.
Under normal conditions the rear heated oxygen sensor is not used for engine control operation.




CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Remarks: Specification data are reference values.




ECM TERMINALS AND REFERENCE VALUE
Remarks: Specification data are reference values, and are measured between each terminal and (25) (ECCS ground) with a voltmeter.




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 the sensor's voltage value and the switching response during the various driving condition such as fuel-cut.

OVERALL FUNCTION CHECK
This procedure can be used for checking the overall function of the rear heated oxygen sensor circuit. During this check, a DTC might not be confirmed.

With Consult
(1) Start engine and warm it up sufficiently.




(2) Select "FUEL INJECTION" in "ACTIVE TEST" mode, and select "RR 02 MNTR" as the monitor item with CONSULT.
(3) Check "RR O2 SENSOR" at idle speed when adjusting
"FUEL INJECTION" to ±25%.

"RR O2 SENSOR" should be above O.48V at least once when the "FUEL INJECTION" is +25%.
"RR O2 SENSOR" should be below O.43V at least once when the "FUEL INJECTION" is -25%.

OR

Without Consult
(1) Start engine and warm it up sufficiently.




(2) Set voltmeter probes between ECM terminals (56) (sensor signal) and (25) (engine ground).
(3) 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 O.48V and below O.43V at least once during this procedure.
If the voltage can be confirmed in step 3, step 4 is not necessary.
(4) Keep vehicle at idling for 10 minutes, then check the voltage. Or check the voltage when coasting from 80 km/h (50 MPH) in 3rd gear position.




The voltage should be above O.48V and below O.43V at least once during this procedure.




WIRING DIAGRAM




DIAGNOSTIC PROCEDURE