Air-Fuel Ratio (A/F) Sensor

1. INSPECT AIR-FUEL RATIO COMPENSATION SYSTEM







a. Measure voltage between terminals of the engine ECM.

CAUTION: Connect test leads from the back side of the connector with the ECM connected.

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

b. Connect the hand-held tester to the DLC3.
c. Select "DATA MONITOR" - "A/FS B1 S1", "A/FS B2 S1" and "O2S B1 S2" to display the monitor.
d. Warm up the A/F sensor with the engine speed at 2,500 rpm for approx. 2 minutes.







e. Keep the engine speed at 2,500 rpm and confirm that the displays of "A/FS B1 S1" and "A/FS B2 S1" are as shown in the illustration.

CAUTION: The illustration differs from the real display.
Only hand-held tester displays the waveform of A/F sensor.

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












2. AIR FUEL RATIO SENSOR
Using an ohmmeter, measure the resistance between the terminals.

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