Air Fuel Ratio Sensor

ON-VEHICLE INSPECTION

1. INSPECT AIR FUEL RATIO SENSOR (for Bank 1 Sensor 1)







a. Measure the resistance of the sensor.

If the resistance is not as specified, replace the sensor.

2. INSPECT AIR FUEL RATIO COMPENSATION SYSTEM







a. Measure the voltage of the ECM connectors.

NOTE: Connect test leads from the back side of the connector. The connectors should not be disconnected from the ECM.

HINT: The voltage between the terminals of the ECM is kept constant regardless of the voltage of the A/F sensor.




b. Connect the intelligent tester to the DLC3.
c. Turn the ignition switch to ON.
d. Select the following menu items: Data List / A/FS B1 S1 and O2S B1 S2.
e. Warm up the A/F sensor with the engine speed at 2,500 rpm for approximately 2 minutes.




f. Keep the engine speed at 2,500 rpm and confirm that the display of "A/FS B1 S1" is as shown in the illustration.

HINT:
- The illustration may slightly differ from the display on the intelligent tester.
- Only the intelligent tester displays the waveform of the A/F sensor.

g. Confirm that the display of "O2S B1 S2" changes between 0 to 1 V with the engine speed at 2,500 rpm.

OK: The voltage output oscillates more than 8 times in 10 seconds.

CAUTION:
- Perform the check immediately after warming the engine up.
- If the voltage variation could not be verified, warm up the heated oxygen sensor again. If it could not be verified even after warming up the sensor again, check for DTCs.