Mazda Car 2005-06

Heated Oxygen Sensor

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Operation



The oxygen sensor supplies the computer with a signal that indicates a rich or lean condition during engine operation. The input information assists the computer in determining the proper air/fuel ratio. A low voltage signal from the sensor indicates too much oxygen in the exhaust (lean condition) and, conversely, a high voltage signal indicates too little oxygen in the exhaust (rich condition).

The oxygen sensor supplies the computer with a signal that indicates a rich or lean condition during engine operation. The input information assists the computer in determining the proper air/fuel ratio. A low voltage signal from the sensor indicates too much oxygen in the exhaust (lean condition) and, conversely, a high voltage signal indicates too little oxygen in the exhaust (rich condition).

Removal & Installation




CAUTION
The temperature of the exhaust system is extremely high after the engine has been run. To prevent personal injury, allow the exhaust system to cool completely before removing sensor from the exhaust system.

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the vehicle on jack stands.
  4.  
  5. Disconnect the HO2S from the engine control sensor wiring.
    NOTE
    If excessive force is needed to remove the sensors lubricate the sensor with penetrating oil prior to removal.

  6.  
  7. Remove the sensors with a sensor removal tool, such as Ford Tool T94P-9472-A or equivalent.
  8.  

To install:

  1. Install the sensor in the mounting boss, and then tighten it to 27-33 ft. lbs.
  2.  
  3. Connect the sensor electrical wiring connector to the engine wiring harness.
  4.  
  5. Lower the vehicle.
  6.  
  7. Connect the negative battery cable.
  8.  


CAUTION
The temperature of the exhaust system is extremely high after the engine has been run. To prevent personal injury, allow the exhaust system to cool completely before removing sensor from the exhaust system.

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the vehicle on jack stands.
  4.  
  5. Disconnect the HO2S from the engine control sensor wiring.
    NOTE
    If excessive force is needed to remove the sensors lubricate the sensor with penetrating oil prior to removal.

  6.  
  7. Remove the sensors with a sensor removal tool, such as Ford Tool T94P-9472-A or equivalent.
  8.  

To install:

  1. Install the sensor in the mounting boss, and then tighten it to 27-33 ft. lbs.
  2.  
  3. Connect the sensor electrical wiring connector to the engine wiring harness.
  4.  
  5. Lower the vehicle.
  6.  
  7. Connect the negative battery cable.
  8.  

Testing



Heater Circuit
  1. Disconnect the HO2S connector.
  2.  
  3. Measure the resistance between the HO2S terminals C and D. Standard value:
    1. Front sensor-3.0-3.6 ohms
    2.  
    3. Rear sensor-5.0-7.0 ohms
    4.  

  4.  
  5. If not as specified, replace the HO2S.
  6.  
  7. If within specifications, check connectors and wiring between the sensor and ECM/PCM.
  8.  

  1. Disconnect the HO2S connector.
  2.  
  3. Measure the resistance between the HO2S terminals C and D. Standard value:
    1. Front sensor-3.0-3.6 ohms
    2.  
    3. Rear sensor-5.0-7.0 ohms
    4.  

  4.  
  5. If not as specified, replace the HO2S.
  6.  
  7. If within specifications, check connectors and wiring between the sensor and ECM/PCM.
  8.  

Oxygen Sensor Circuit
  1. Warm up the engine and run it at idle.
  2.  
  3. Disconnect the HO2S connector.
  4.  
  5. Connect the voltmeter positive test lead terminal A and negative test lead to terminal B.
  6.  
  7. With the vehicle stopped, run the engine at 3,000 rpm until the voltmeter moves between 0.5 and 0.7 V.
  8.  
  9. Measurement the voltage changes when the engine speed increases and decreases suddenly several times. Standard value:
    1. Acceleration-0.5-1.0 volt
    2.  
    3. Deceleration-0-0.5 volt
    4.  

  10.  
  11. If not as specified, replace the HO2S.
  12.  
  13. If within specification, check wiring harness and connectors between HO2S and PCM.
  14.  

  1. Warm up the engine and run it at idle.
  2.  
  3. Disconnect the HO2S connector.
  4.  
  5. Connect the voltmeter positive test lead terminal A and negative test lead to terminal B.
  6.  
  7. With the vehicle stopped, run the engine at 3,000 rpm until the voltmeter moves between 0.5 and 0.7 V.
  8.  
  9. Measurement the voltage changes when the engine speed increases and decreases suddenly several times. Standard value:
    1. Acceleration-0.5-1.0 volt
    2.  
    3. Deceleration-0-0.5 volt
    4.  

  10.  
  11. If not as specified, replace the HO2S.
  12.  
  13. If within specification, check wiring harness and connectors between HO2S and PCM.

    Click image to see an enlarged view

    Fig. Front heated oxygen sensor connector-Mazda 6 L4



    Click image to see an enlarged view

    Fig. Rear heated oxygen sensor connector-Mazda 6 L4

  14.  

 
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