Air Fuel Ratio Sensor

ON-VEHICLE INSPECTION




1. INSPECT AIR FUEL RATIO SENSOR
a. Disconnect the 2 sensor connectors.




b. Measure the heater resistance according to the value(s) in the table.

If the result is not as specified, replace the air fuel ratio sensor.

c. Connect the 2 sensor connectors.

2. INSPECT AIR-FUEL RATIO COMPENSATION SYSTEM

HINT: Malfunctioning areas can be identified by performing the A/F CONTROL*1 (Control the Injection Volume for A/F sensor*2) function provided in the Active Test. The A/F CONTROL (Control the Injection Volume for A/F sensor) function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the A/ F CONTROL (Control the Injection Volume for A/F sensor) operation using the intelligent tester or Techstream.
*1: Intelligent tester
*2: Techstream

1. Connect the intelligent tester or Techstream to the DLC3.
2. Start the engine and turn the tester ON.
3. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
4. Enter the following menus:(a)Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.(b)Techstream - Select: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.

5. Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).







6. Monitor the output voltages of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.

HINT:
- The A/F CONTROL (Control the Injection Volume for A/F sensor) operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

NOTE: The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.

- Following the A/F CONTROL or Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the A/ F and HO2 sensors.

- To display the graph, enter the following menus:
1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / A/F CONTROL SYS / AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2; then press the YES button and the ENTER button followed by the F4 button.
2. Techstream - Select: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS B1 S1 and O2SB1 S2 or AFS B2 S1 and O2S B2 S2.