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EC-212 < COMPONENT DIAGNOSIS > [QR25DE] P0143 HO2S3 P0143 HO2S3 Description INFOID:0000000004211449 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 volt- age from approximately 1V in richer conditions to 0V in leaner condi- tions. Under normal conditions the heated oxygen sensor 3 is not used for engine control operation. DTC Logic INFOID:0000000004211450 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 oxy- gen 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 conduct- ing 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” ( ) 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. SEF327R PBIB2376E DTC No. Trouble diagnosis name DTC detecting condition Possible cause P0143 Heated oxygen sensor 3 The minimum voltage from the sensor is not • Harness or connectors (The sensor circuit is open or shorted) • Heated oxygen sensor 3 |