P0143

P0143 HO2S3





Description





The heated oxygen sensor 3, after HC adsorption catalyst (Under floor), monitors the oxygen level in the exhaust gas.
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 heated oxygen sensor 3 is not used for engine control operation.




DTC Logic

DTC DETECTION LOGIC





The heated oxygen sensor 3 has a much longer switching time between rich and lean than the air fuel ratio (A/F) sensor 1. The oxygen storage capacity of the three way catalyst (manifold) causes the longer switching time. To judge the malfunctions of heated oxygen sensor 3, ECM monitors whether the minimum voltage of sensor is sufficiently low during the various driving condition such as fuel cut.






DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next test.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
- GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Activate "INSPECTION MODE 1" ( Mode 1) to start engine, and warm up engine to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Turn ignition switch ON (READY).
6. Repeat following procedure 3 times.
- Drive vehicle at a speed of 80 km/h (50 MPH) or more for at least 3 consecutive minutes.

CAUTION:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws.

NOTE:
- Keep the vehicle speed as steady as possible during the cruising.
- Never raise engine speed above 3,600 rpm in this step.
- Release accelerator pedal fully and stop vehicle.

NOTE:
Never turn ignition switch OFF.
7. Check 1st trip DTC.
Is 1st trip DTC detected?
YES - Go to P0143.
NO - INSPECTION END




Diagnosis Procedure
1.CHECK GROUND CONNECTION
1. Turn ignition switch OFF.
2. Check ground connection E9. Refer to Ground Inspection in Circuit Inspection.
Is the inspection result normal?
YES - GO TO 2.
NO - Repair or replace ground connection.
2.CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE
1. Clear the mixture ratio self-learning value. Special Repair Requirement.
2. Activate "INSPECTION MODE 1" ( Mode 1) to start engine, and let engine idle for at least 10 minutes.
Is the 1st trip DTC P0172 detected? Is it difficult to start engine?
YES - Perform trouble diagnosis for DTC P0172. P0172.
NO - GO TO 3.
3.CHECK HO2S3 GROUND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect heated oxygen sensor 3 harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between HO2S3 harness connector and ECM harness connector.





5. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES - GO TO 5.
NO - GO TO 4.
4.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors F58, F201
- Harness for open or short between heated oxygen sensor 3 and ECM
- Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK HO2S3 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check the continuity between HO2S3 harness connector and ECM harness connector.





2. Check the continuity between HO2S3 harness connector or ECM harness connector and ground.





3. Also check harness for short to power.
Is the inspection result normal?
YES - GO TO 7.
NO - GO TO 6.
6.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors F58, F201
- Harness for open or short between heated oxygen sensor 3 and ECM
- Repair open circuit or short to ground or short to power in harness or connectors.
7.CHECK INTERMITTENT INCIDENT
Intermittent Incident.
Is the inspection result normal?
YES - GO TO 8.
NO - Repair or replace.
8.REPLACE HEATED OXYGEN SENSOR 3
Replace heated oxygen sensor 3.

CAUTION:
- Discard any 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.
- Before installing new sensor, clean exhaust system threads using oxygen sensor thread cleaner
[commercial service tool: (J-43897-18 or J-43897-12)] and approved anti-seize lubricant (commercial service tool).
- INSPECTION END