Pickup 1997

Heated Oxygen Sensor

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Component Description



Specific to:

Nissan Pickup 1996-1997

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.

Location



Specific to:

Nissan Pickup 1996-1997



Click image to see an enlarged view

Fig. Front and rear heated oxygen sensor locations

Operation



Fuel Trim

Specific to:

Nissan Pickup 1996-1997

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:

Nissan Pickup 1996-1997

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

Removal & Installation



Specific to:

Nissan Pickup 1996-1997

At this time the manufacturer does not provide removal and installation procedures for this component. The following procedure is a guideline and may differ from the vehicle you are servicing.

The oxygen sensor is installed in the exhaust system between the exhaust valves and the catalytic converter. It is often placed close to the engine for quick and efficient warm-up.

The oxygen sensor is removed in the same manner as a spark plug. Exercise care when handling the sensor. Do not drop or handle the sensor roughly. When installing a new oxygen sensor, use care not to get the anti-seize compound (which is normally found on the sensor's threads) on your fingers. More importantly, make sure you do NOT get any on the probe end of the sensor. If reinstalling an old oxygen sensor, you must reapply the anti-seize compound to the sensor.

  1. Before servicing the vehicle, refer to the Precautions Section.
    NOTE
    If working near and/or around the SRS system and components, be sure to disable the SRS system. After disabling the system wait three minutes or more before servicing the vehicle. Disconnect the air bag module connector.



    Click image to see an enlarged view

    Fig. Air bag module connector location

  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Raise and safely support the vehicle, as required.
  6.  
  7. Unplug the wiring connector leading from the O 2 sensor.
  8.  
  9. Unscrew the sensor from its mounting.

    Click image to see an enlarged view

    Fig. Front and rear heated oxygen sensors



    Click image to see an enlarged view

    Fig. Exhaust system and related components-2WD



    Click image to see an enlarged view

    Fig. Exhaust system and related components-4WD

  10.  

To install:


NOTE
Be sure to use new fasteners, as required.

  1. If not already on the sensor, coat the threads of the replacement sensor with a nickel base anti-seize compound. Do not use other types of compounds, since they may electrically insulate the sensor.
  2.  
  3. Install the sensor into the exhaust system. Torque the sensor to 18-25 ft. lbs. (24-34 Nm). Connect the electrical lead. Be careful handling the electrical lead as it is easily damaged.
  4.  
  5. Reconnect the battery cable.
  6.  
  7. Using the CONSULT-III diagnostic tool, or equivalent, perform the SRS self diagnostic test and any reconnect/relearn procedures, as required.
  8.  

Testing



Specific to:

Nissan Pickup 1996-1997


NOTE
Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.

Connection & Wiring Diagnosis

Specific to:

Nissan Pickup 1996-1997

Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.

Many intermittent open or short circuits may be caused by wiring harness and connector movement due to vibration, engine torque, bumps and rough pavement, etc.

  1. Test the wiring harness and connectors by performing the following tests:

    Move the related connectors and wiring while monitoring the appropriate scan tool data.
     
    Move the related connectors and wiring with the component commanded ON and OFF. Using a suitable the scan tool, observe the component operation.
     
    With the engine running, move the related connectors and wiring while monitoring component operation.
     
    If harness or connector movement affects the data displayed, the component and system operation, or the engine operation, inspect and repair the harness or connections as necessary.
     

  2.  
  3. Test the connector terminal pins and/or wiring by performing the following tests:

    Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body.
     
    Inspect for improperly formed or damaged terminals and test for incorrect terminal tension.
     
    Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body.
     
    Inspect for corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation with little visible evidence. Look for swollen and/or brittle sections of wire in the suspect circuits.
     
    Inspect for wires that are broken inside the insulation by gently pulling on suspect sections of wiring.
     

  4.  

Heated Oxygen Sensor Strategy

Specific to:

Nissan Pickup 1996-1997

The oxygen sensor operates most effectively when an operating temperature of 1,472° F (800° C) or higher is reached and maintained. When the oxygen sensor reaches the specified temperature and begins sending the feedback signal, the PCM uses the information to enter closed loop mode, which is defined as the PCM having full control of the air-fuel ratio. In order to achieve operating temperature and enter closed loop more quickly, modern oxygen sensors have built-in heating elements.

Oxygen Sensor Heater

Specific to:

Nissan Pickup 1996-1997

The oxygen sensor heater may be tested by performing a resistance test; the sensor must be disconnected from the main engine wiring harness. If the circuit resistance is greater than 5.0 ohms, replace the HO2S. Refer to the Electrical Wiring Diagram for specific circuit information and connector views.

Click image to see an enlarged view

Fig. Normal pre-catalyst HO2S reading



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Fig. Normal post-catalyst HO2S reading

Post-Catalyst Sensor 2

Specific to:

Nissan Pickup 1996-1997

A properly operating #2, or rear heated oxygen sensor (HO2S) should display flat feedback voltage of less than 0.2 volts DC . Use a suitable scan tool or a Graphing Multi-Meter (GMM) in order to view HO2S data.

If the feedback signal displays a cross-count, this is usually an indication of a faulty catalytic converter. If the feedback signal is flat, but is greater than 0.5 volts DC, additional diagnosis is required in order to determine the proper function of the HO2S, or if a fault exists in any related sub-systems.

Pre-Catalyst Sensor 1

Specific to:

Nissan Pickup 1996-1997

A properly operating #1, or front heated oxygen sensor (HO2S) should display a cross count of eight oscillations or more within ten seconds, within a voltage range of 0.2- 0.8 volts Cause a suitable scan tool or a Graphing Multi-Meter (GMM) in order to view HO2S data.

If the feedback signal is not within the specified range, additional diagnosis is required in order to determine the proper function of the HO2S, or if a fault exists in any related sub-systems.

Related Diagnostic Trouble Codes

Specific to:

Nissan Pickup 1996-1997



Click image to see an enlarged view

Fig. Related Diagnostic Trouble Codes

 
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