Front O2 Sensor, Bank 2

The front heated oxygen sensor (left bank) is placed into the front tube (left bank). It detects the amount of oxygen in the exhaust gas compared to the outside air. The front heated oxygen sensor (left bank) has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. The front heated oxygen sensor (left bank) signal is sent to the ECM. The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1V to 0V.







DIAGNOSTIC CHART




OVERALL FUNCTION CHECK
This procedure can be used for checking the overall function of the front 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 "MANU TRIG" and "HI SPEED" in "DATA MONITOR" mode with CONSULT, and select "FR O2 SEN-B2" and "FR O2 MNTR-B2".
3) Hold engine speed at 2,000 rpm under no load during the following steps.




4) Touch "RECORD" on CONSULT screen.
5) Make sure of the following.

- "FR O2 MNTR-B2" in "DATA MONITOR" mode changes from "RICH" to "LEAN" to "RICH" 5 times in 10 seconds.
5 times (cycles) are counted as shown below:

cycle | 1 | 2 | 3 | 4 | 5 |
FR O2 MNTR-B2 R-L-R-L-R-L-R-L-R-L-R

R = "FR O2 MNTR-B2", "RICH"
L = "FR O2 MNTR-B2", "LEAN"




- "FR O2 SEN-B2" voltage goes above O.6 V at least once.
- "FR O2 SEN-B2" voltage goes below 0.35 V at least once.
- The voltage never exceeds 1.0 V.

OR

NO TOOLS
1) Start engine and warm it up sufficiently.




2) Set voltmeter probes between ECM terminal (51) (sensor signal) and (25) (engine ground).
3) Make sure of the following with engine speed held at 2,000 rpm constant under no load.
- Malfunction indicator lamp goes on more than 5 times within 10 seconds in Diagnostic Test Mode II (FRONT HEATED OXYGEN SENSOR MONITOR).
- The maximum voltage is over O.6 V at least one time.
- The minimum voltage is below 0.35 V at least one time.
- The voltage never exceeds 1.0 V.


COMPONENT INSPECTION

Front heated oxygen sensor heater




Check resistance between terminals (3) and (1).

Resistance: 2.3 - 4.3ohms at 25°C (77°F)

Check continuity between terminals (2) and (1) (3) and (2).

Continuity should not exist.

If NG, replace the front heated oxygen sensor.




WIRING DIAGRAM