Non-California Models

DESCRIPTION
The front HO2S is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The sensor has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1 Volt in richer conditions to O Volts in leaner conditions. The sensor 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 1 Volt to O Volts.




DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the front 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 SENSOR" and "FR O2 MNTR".
3. Hold engine speed at 2,000 rpm under no load during the following steps.
4. Touch "RECORD" on CONSULT screen.




5. Check the following.
- "FR O2 MNTR" 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 R-L-R-L-R-L-R-L-R-L-R
R = "FR O2 MNTR", "RICH"
L = "FR O2 MNTR", "LEAN"

- "FR 02 SENSOR" voltage goes above 0.6V at least once.
- "FR 02 SENSOR" voltage goes below 0.35V at least once.

OR

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




2. Set voltmeter probes between ECM terminal (46) (sensor signal) and (43) (engine ground).
3. Check 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 OXYGEN SENSOR* MONITOR).
- The maximum voltage is over 0.6V at least one time.
- The minimum voltage is below 0.35V at least one time.




WIRING DIAGRAM







DIAGNOSTIC 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.