Forenza 2007

Heated Oxygen Sensor

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Operation



Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008

Heated Oxygen Sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the vehicle is first started, the Engine Control Module (ECM) operates in an open loop mode, ignoring the HO2S signal voltage when calculating the air fuel ratio. The ECM supplies the HO2S with a reference voltage of about 0.45 Volts. The HO2S generates a voltage within a range of 0 -1 volts that fluctuates above and below bias voltage once in closed loop. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature, and then provide an accurate voltage signal.

Removal & Installation



Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008


CAUTION
To avoid danger of being burned, do not touch exhaust system when system is hot. Oxygen sensor removal should be performed when system is cool.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the heat shield with the bolts.
  4.  
  5. Disconnect connector of the heated oxygen sensor and release its wire harness from clamps.
  6.  
  7. Remove exhaust manifold cover.
  8.  
  9. Remove heated oxygen sensor (1) from exhaust manifold.

    Click image to see an enlarged view

    Fig. Heated Oxygen Sensor (HO2S) 1 location

  10.  

To install:


CAUTION
A special anti-seize compound is used on the heated oxygen sensor threads. This compound consists of a liquid graphite and glass beads. The graphite will burn away, but the glass beads will remain, making the sensor easier to remove. New or serviced sensors will already have the compound applied to the threads. If a sensor is removed from any engine and is to be reinstalled, the threads must have an anti-seize compound applied before reinstallation.

  1. Coat the threads of the HO2S 1 with an anti-seize compound.
  2.  
  3. Install and tighten the HO2S 1 to 31 ft. lbs. (42 Nm).
  4.  
  5. Connect the connector of the HO2S 1and clamp wire harness securely.
  6.  
  7. Install the heat shield and tighten the bolts to 11 ft. lbs. (15 Nm).
  8.  
  9. After installing the sensor, start engine and check that no exhaust gas leakage exists.
  10.  

Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008


CAUTION
To avoid danger of being burned, do not touch exhaust system when system is hot. Oxygen sensor removal should be performed when system is cool.

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect connector of the HO2S 2 and release its wire harness from clamps.
  4.  
  5. Remove the HO2S 2 from exhaust pipe.
    WARNING



    Click image to see an enlarged view

    Fig. Heated Oxygen Sensor 2 (HO2S 2) location

  6.  

To install:

  1. Install and tighten the HO2S 2 to 31 ft. lbs. (42 Nm).
  2.  
  3. Attach the connector of the HO2S 2 and clamp wire harness securely.
  4.  
  5. Connect the negative battery cable.
  6.  

Testing



Specific to:

Suzuki Forenza 2007-2008

Suzuki Reno 2007-2008

  1. Start the engine.
  2.  
  3. Allow the engine to reach operating temperature.
  4.  
  5. Operate the engine at 1.500 rpm for 30 seconds.
  6.  
  7. While observing the HO2S voltage parameter with a scan tool, quickly cycle the throttle from closed throttle to wide open throttle (WOT), 3 times.
  8.  
  9. The HO2S voltage parameter should change more than 200 mV.
  10.  
  11. If the voltage does not change more that the specified value, the condition is present to set a Diagnostic Trouble Code (DTC).
  12.  
  13. Observe the Freeze Frame/Failure Records for this DTC.
  14.  

Heater Testing
  1. Disconnect sensor connector.
  2.  
  3. Using ohmmeter, measure resistance between terminals -VB- and -GND- of sensor connector.
  4.  
  5. Readings should be 2-6 ohms at 68°F, 20°C for sensor.
  6.  
  7. Readings should be 4-10 ohms at 68°F, 20°C for sensor 2.
    NOTE
    If found faulty, replace oxygen sensor.

  8.  

 
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