On-Vehicle Inspection

INSPECT AIR FUEL RATIO SENSOR

Disconnect the sensor connector.

Measure the heater resistance of the sensor.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Condition	Specified Condition
1 (HT) - 2 (+B)	20°C (68°F)	1.8 to 3.4 Ω

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

Fig 1: Identifying Air Fuel Ratio Sensor Connector Terminals

G05287281

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INSPECT AIR-FUEL RATIO COMPENSATION SYSTEM
1. Connect the intelligent tester to the DLC3.
2. Turn the engine switch ON (IG).
3. Select the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / A/FS B1 S1, A/FS B2 S1, O2S B1 S2 and O2S B2 S2.
4. Warm up the A/F sensor by running the engine at 2, 500 rpm for approximately 2 minutes.
5. Keep the engine speed at 2500 rpm and confirm that the displays of "A/FS B1 S1" and "A/FS B2 S1" are as shown in the illustration.
  
  Fig 2: Connecting Intelligent Tester To DLC3
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 3: Air-Fuel Ratio Graph
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  HINT:
  - The illustration may slightly differ from the display on the intelligent tester.
  - The waveform of the A/F sensor is displayed only on the intelligent tester.
6. 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.
  NOTE:
  - Perform the check immediately after warming up the engine.
  - If the voltage oscillation could not be verified, warm up the heated oxygen sensor again. If it is still not possible to verify, perform a DTC check (see DIAGNOSTIC TROUBLE CODE CHART ).