AIR FUEL RATIO (A/F) SENSOR INSPECTION [MZI-3.7]

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A/F Sensor Inspection

1. Connect the M-MDS to the DLC-2.

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2. Warm up the engine to normal operating temperature.

3. Drive the vehicle.

4. Release the accelerator pedal while the engine speed is at 3,000 rpm or more and verify that the following monitor items fluctuate as shown in the figure while the vehicle decelerates. (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7].)

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  • VSS (Vehicle speed)
  • RPM (Engine speed)
  • O2S11, O2S21 (A/F sensor output current)
    ― If not within the specification, replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [MZI-3.7].)

A/F Sensor Heater Inspection

1. Disconnect the negative battery cable. (See BATTERY REMOVAL/INSTALLATION [MZI-3.7].)

2. Disconnect the A/F sensor connector.

3. Measure the resistance between A/F sensor terminals C and E.

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  • If it is not within the specification, replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [MZI-3.7].)

  A/F sensor heater resistance

  1—10 ohms