Code 0512

DTC 0512 (Right Bank, -B1) Rear Heated Oxygen Sensor (Rear HO2S) (High Voltage)

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 (ECCS 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 voltage is unusually high during the various driving condition such as fuel-cut.

DTC Confirmation Procedure

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.

With CONSULT
1. Turn ignition switch "ON" and select "DATA MONITOR" mode with CONSULT.
2. Meet the following conditions once.
CMPS-RPM (REF): 1,300 - 2,800 rpm
VHCL SPEED SE: 64 - 120 km/h (40 - 75 MPH)
B/FUEL SCHDL: 1.7 - 6.4 ms
COOLAN TEMP/S: 70 - 100°C (158 - 212°F)
Selector lever: Suitable position
3. Stop vehicle with engine running.

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.

Steps 1 - 2:

Steps 3 - 7:

Diagnostic Procedure

Wiring Diagram - Right Bank

Component Inspection

With CONSULT
1. Start engine and warm it up to normal operating temperature.
2. Select "FUEL INJECTION" in "ACTIVE TEST" mode and select "RR O2 SEN-B1 (-B2)" as the monitor item with CONSULT
3. Check "RR O2 SEN-B1 (-B2)" at idle speed when adjusting FUEL INJECTION" to ±25%.
"RR O2 SEN-B1 (-B2)" should be above 0.48V at least once when the "FUEL INJECTION" Is +25%.
"RR O2 SEN-B 1 (-B2)" should be below 0.43V at least once when the "FUEL INJECTION" Is -25%.

Without CONSULT
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 56 (right bank sensor signal) or 57 (left bank sensor signal) and 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 0.48V at least once during this procedure.
If the voltage is above 0.48V at 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 below 0.43V 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.