DTC 0303
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 (25) (ECM ground).
ON BOARD DIAGNOSIS LOGIC
Under the condition in which the front heated oxygen sensor signal is not input, the ECM circuits will read a continuous approximately 0.3 V. Therefore, for this diagnosis, the time that output voltage is within 200 to 400 mV range is monitored, and the diagnosis checks that this time is not inordinately long.
DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
CAUTION: Always drive vehicle at a safe speed.
NOTE: If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.
TESTING CONDITION:
- Never raise engine speed above 3,600 rpm (A/T), 4,000 rpm (M/T) during the "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE". If the engine speed limit is exceeded, retry the procedure from step 4.
- Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.
With Consult
1. Start engine and warm it up to normal operating temperature.
2. Select "FR O2 SEN-B1 (-B2) P0130 (P0150)" of "FRONT O2 SENSOR" in "DTC WORK SUPPORT" mode with CONSULT.
3. Touch "START".
4. Let it idle for at least 3 minutes.
5. When the following conditions are met, "TESTING" will be displayed on the CONSULT screen. Maintain the conditions continuously until "TESTING" changes to "COMPLETED". (It will take approximately 10 to 60 seconds.)
CKPS.RPM (POS): 1,400 - 2,400 rpm (A/T models) 1,600 - 2,600 rpm (M/T models)
Vehicle speed: 70 - 100 KPH (43 - 62 MPH)
B/FUEL SCHDL: 1 - 5 ms
Selector lever: Suitable position
If "TESTING" is not displayed after 5 minutes, retry from step 2.
6. Make sure that "OK" is displayed after touching "SELF- DIAG RESULTS". If "NG" is displayed, refer to "DIAGNOSTIC PROCEDURE".
During this test, P1148 may be stored in ECM.
OR
OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the front heated oxygen sensor circuit. During this check, a 1st trip DTC might not be confirmed.
Without Consult
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal (50) RH, (51) LH (sensor signal) and ground.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
- The voltage does not remain in the range of 0.2 - 0.4 V.
4. If NG, go to "DIAGNOSTIC PROCEDURE".
WIRING DIAGRAM
DIAGNOSTIC PROCEDURE
COMPONENT INSPECTION
With Consult
1. Start engine and warm it up to normal operating temperature.
2. Select "MAN U TRIG" and "HI SPEED" in "DATA MONITOR" mode with CONSULT, and select "FR O2 SEN-B1 (-B2)" and "FR O2 MNTR-B1 (-B2)".
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-B1 (-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-B1 R-L-R-L-R-L-R-L-R-L-R
R = "FR O2 MNTR-B1 (-B2)", "RICH"
L = "FR O2 MNTR-B1 (-B2)", "LEAN"
- "FR O2 SEN-B1 (-B2)" voltage goes above 0.6 V at least once.
- "FR O2 SEN-B1 (-B2)" voltage goes below 0.35 V at least once.
- "FR O2 SEN-B1 (-B2)" 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.
OR
Without Consult
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal (50) RH, (51) LH (sensor signal) and 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 HEATED OXYGEN SENSOR MONITOR).
- The maximum voltage is over 0.6 V at least one time.
- The minimum voltage is below 0.35 V at least one time.
- The voltage never exceeds 1.0 V.
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.