HEATED OXYGEN SENSOR (HO2S) INSPECTION [MZI-3.7]

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HO2S Inspection

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

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2. Warm up the engine to normal operating temperature.

3. Access the following PIDs using the M-MDS: (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7].)

  • VSS (Vehicle speed)
  • RPM (Engine speed)
  • O2S12, O2S22 (HO2S output voltage)

4. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.

5. Verify that the HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the HO2S output voltage (PID: O2S12, O2S22) is 0.3 V or less while decelerating as shown in the figure.

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  • If not within the specification, inspect the HO2S for an open or short circuit.
    ― Then if there is no malfunction in the wiring harness, replace the HO2S. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [MZI-3.7].)

HO2S Heater Inspection

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

2. Disconnect the HO2S connector.

3. Measure the resistance between HO2S terminals A and C.

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  • If it is not within the specification, replace the HO2S. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [MZI-3.7].)

  HO2S heater resistance

  2―50 ohms