Air Fuel Ratio Sensor (For Sensor 1) On-Vehicle Inspection

Disconnect the A/F sensor connector.

Measure the heater resistance between terminals 1 (HT) and 2 (+B) of the sensor.

Standard resistance:

1.8 to 3.4 Ω at 20°C (68°F)

Measure the voltage between the terminals of the ECM connectors.

Standard resistance:

Tester Connection	Condition	Specified Condition
E45-18 (A1A+) - E7-7 (E1)	Engine switch on (IG)	3.3 V
E45-17 (A1A-) - E7-7 (E1)	Engine switch on (IG)	2.9 V
E45-28 (A2A+) - E7-7 (E1)	Engine switch on (IG)	3.3 V
E45-27 (A2A-) - E7-7 (E1)	Engine switch on (IG)	2.9 V

NOTICE:

1. Connect the tester leads from the backside of the connector. The connector should not be disconnected from the ECM.
   
2. The voltage between the terminals of the ECM is kept constant regardless of the voltage of the A/F sensor.
   

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG).

Select the following menus: Powertrain / Engine / Data List / A/FS B1 S1, A/FS B2 S1, O2S B1 S2 and O2S B2 S2.

Warm up the A/F sensor by running the engine at 2, 500 rpm for approximately 2 minutes.

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.

HINT:

1. The illustration may slightly differ from the display on the intelligent tester.
   
2. The waveform of the A/F sensor is displayed only on the intelligent tester.
   

Check the displays of "O2S B1 S2" and "O2S B2 S2" with the engine speed at 2,500 rpm.

Standard condition:

Displays show that each voltage fluctuates between 0 and 1 V.

NOTICE:

1. Perform the check immediately after warming up the engine.
   
2. If the voltage oscillation could not be verified, warm up the heated oxygen sensor again. If it is still not possible to verify, perform DTC check (Click here).