Code 0412
COMPONENT DESCRIPTION
The front heated oxygen sensor is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The front heated oxygen sensor has a closed- end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer conditions to 0 V in leaner conditions. The front heated oxygen 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 V to 0 V.
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 43 (ECM ground).
ON BOARD DIAGNOSIS LOGIC
To judge the malfunction, the diagnosis checks that the front heated oxygen sensor output is not inordinately high.
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. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Turn ignition switch "ON".
4. Select "DATA MONITOR" mode with CONSULT.
5. Restart engine and let it idle for 2 minutes.
6. If 1st trip DTC is detected, go to "Diagnostic Procedure".
With GST
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Restart engine and let it idle for 2 minutes.
4. Turn ignition switch "OFF" and wait at least 5 seconds.
5. Restart engine and let it idle for 2 minutes.
6. Select "MODE 3" with GST.
7. If DTC is detected, go to "Diagnostic Procedure".
Without Scan Tools
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch "OFF" and wait at least 5 seconds.
3. Restart engine and let it idle for 2 minutes.
4. Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
5. Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
6. If 1st trip DTC is detected, go to "Diagnostic Procedure".
- When using GST, "DTC Confirmation Procedure" should be performed twice as much as when using CONSULT or ECM (Diagnostic Test Mode II) because GST cannot display MODE 7 (1st trip DTC) concerning this diagnosis. Therefore, using CONSULT or ECM (Diagnostic Test Mode II) is recommended.
WIRING DIAGRAM
1 RETIGHTEN FRONT HEATED OXYGEN SENSOR:
2 CHECK INPUT SIGNAL CIRCUIT:
3 CHECK HARNESS CONNECTOR:
4 CHECK FRONT HEATED OXYGEN SENSOR:
5 CHECK SHIELD CIRCUIT:
6 CHECK INTERMITTENT INCIDENT:
DIAGNOSTIC PROCEDURE
COMPONENT INSPECTION
With CONSULT
1. Start engine and warm it up to normal operating temperature.
2. Select "MANU TRIG" and "HI SPEED" in "DATA MONITOR" mode, 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" five times in 10 seconds.
5 times (cycles) are counted as shown below:
R = "FR O2 MNTR", "RICH"
L = "FR O2 MNTR", "LEAN"
- "FR O2 SENSOR" voltage goes above 0.6 V at least once.
- "FR O2 SENSOR" voltage goes below 0.3 V at least once.
- "FR O2 SENSOR" voltage never exceeds 1.0 V.
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.
Without CONSULT
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 46 (Front heated oxygen sensor signal) and 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 five times within 10 seconds in Diagnostic Test Mode II (FRONT HEATED OXYGEN SENSOR MONITOR).
- The maximum voltage is over 0.6 V at least one time.
- The minimum voltage is below 0.3 V at least one time.
- The voltage never exceeds 1.0 V.
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.