Protege 1999-2000

Heated Oxygen Sensor

Print

Operation



Specific to:

Mazda Protege 1999-2003

Mazda Protege5 2002-2003

The Oxygen Sensor is a zirconium dioxide electronic device that measures the proportion of oxygen (O2) content in the exhaust gas. The sensor operates by measuring the difference between the oxygen content in the exhaust gas and the external air, and generates a variable voltage signal as the ratio between the two changes. The function of the oxygen sensor is to monitor the Air-Fuel ratio of the engine, determine if the mixture is rich or lean, and provide feedback (real-time information) to the Powertrain Control Module (PCM) so that the Air-Fuel ratio may be automatically adjusted.

Fuel Trim

Specific to:

Mazda Protege 1998-2003

Mazda Protege5 2002-2003

Fuel trim is the PCM parameter that is used to adjust the Air-Fuel mixture. The ideal HO2S feedback value is 0.45 volts DC, which is indicated when air and fuel are at the stoichiometric ratio of 14.7:1. This value is determined by oxygen sensor feedback, and provides the final data for the PCM in determining the correct Air-Fuel mixture.

Oxygen Sensor Heater

Specific to:

Mazda Protege 1998-2003

Mazda Protege5 2002-2003

In order to achieve operating temperature and enter closed loop more quickly, modern oxygen sensors have built-in heating elements.

Removal & Installation



Specific to:

Mazda Protege 1999-2003


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



1.6L Engine
Circuit Open/Short Inspection

Specific to:

Mazda Protege 1998-2001

  1. Remove the PCM. See -Powertrain Control Module (PCM)- in this section.
  2.  
  3. Connect the 104-Pin Breakout Box) to the PCM as shown.
  4.  
  5. Tighten the connector attaching screw.
  6.  
  7. Inspect for an open or short circuit in the following wiring harnesses by probing the applicable sensor and 104-Pin Breakout Box terminals with ohmmeter leads.
    1. If there is an open or short circuit, repair or replace wiring harnesses.
    2.  
    3. If there is no open or short circuit, replace the HO2S.
    4.  

  8.  
  9. To check for open circuit:

    HO2S signal circuit (HO2S connector terminal A and PCM connector terminal 60 (Front), 35 (Rear))
     
    GND circuit (HO2S connector terminal B and PCM connector terminal 91)
     

  10.  
  11. To check for short circuit:

    HO2S signal circuit (HO2S terminal A and PCM connector terminal 60 (Front), 35 (Rear) to GND)

    Click image to see an enlarged view

    Fig. Showing the front and rear HO2S connector pin arrangement-harness side connectors

     

  12.  
  13. Reconnect the HO2S connector.
  14.  

HO2S (Front And Rear) Voltage Inspection

Specific to:

Mazda Protege 1998-2001

  1. Warm up the engine and run it at idle.
  2.  
  3. Disconnect the HO2S (Front or Rear) connector.
  4.  
  5. Connect the voltmeter test leads to the following HO2S terminals:

    (+) lead-HO2S terminal A
     
    (-) lead-HO2S terminal B

    Click image to see an enlarged view

    Fig. Showing the HO2S connector pin arrangement-component side connector

     

  6.  
  7. Run the engine at 3,000 RPM until the voltmeter indicates approximately 0-1.0 V.
  8.  
  9. Verify that the voltmeter needle moves when the engine speed increases and decreases suddenly several times.
    1. If not as specified, replace the HO2S.

      As engine speed increases, voltage should range from 0.5-1.0 V
       
      As engine speed decreases, voltage should range from 0-0.5 V
       

    2.  
    3. If the HO2S is okay, but PID value or PCM terminal 60 (Front), 35 (Rear) voltage are out of specification, carry out the -Circuit Open/Short Inspection-.
    4.  

  10.  

HO2S Heater (Front And Rear) Resistance Inspection

Specific to:

Mazda Protege 1998-2001

  1. Disconnect the HO2S (Front or Rear) connector.
  2.  
  3. Measure the resistance between HO2S terminals C and D using an ohmmeter.
  4.  
  5. If not as specified, replace the HO2S.

    Front HO2S should be approximately 5.6 ohms
     
    Rear HO2S should be approximately 15.7 ohms
     

    1. If the HO2S heater is okay, but PID value or PCM terminal 94 (Front), 93 (Rear) voltage are out of specification, carry out the -Circuit Open/Short Inspection-.

      Click image to see an enlarged view

      Fig. Showing the front and rear HO2S connector pin arrangement-component side connectors

    2.  

  6.  

Heater Circuit

Specific to:

Mazda Protege 1999-2003

  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

Specific to:

Mazda Protege 1999-2003

  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.



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.

  14.  

 
label.common.footer.alt.autozoneLogo