CR-V 2007-2008

Heated Oxygen Sensor

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Operation



Specific to:

Honda CR-V 2007-2008

The Heated Oxygen Sensor (HO2S) consists of zirconium and alumina and is installed upstream and downstream of the 3-way catalytic converter. After it compares the oxygen consistency of the atmosphere with the exhaust gas, it transfers the oxygen consistency of the exhaust gas to the PCM. This sensor operates most efficiently when the temperature of the sensor tip is higher than 698°F (370°C). Therefore, a heater has been integrated with the oxygen sensor that is controlled by the PCM duty signal. When the exhaust gas temperature is lower than the specified value, the heater warms the sensor tip. The PCM commands the heater ON or OFF to maintain a specific HO2S operating temperature range. The PCM monitors the voltage on the HO2S heater low control circuit for heater fault diagnosis. If the PCM detects that the HO2S heater low control circuit voltage is not within a specified range, a DTC is set.

The HO2S supplies the electronic control assembly with a signal indicating either a rich or lean mixture condition as the engine operates.

The PCM compares the HO2S output with the A/F sensor output to determine catalyst efficiency.

Removal & Installation



Air Fuel Ratio (A/F) Sensor 1

Specific to:

Honda CR-V 2007-2008

Special tool required:



O2 sensor wrench, Snap-On® S3176, or equivalent
 


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 before removing the sensor from the exhaust system.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the A/F sensor 4P connector (A).
  4.  
  5. Remove the A/F sensor (B).
  6.  

To install:

  1. Install the A/F sensor (B) and tighten to 33 ft. lbs. (44 Nm).
  2.  
  3. Connect the A/F sensor 4P connector (A).

    Click image to see an enlarged view

    Fig. Removing the Air Fuel Ratio (A/F) Sensor 1

  4.  

Heated Oxygen (HO2S) Sensor 2

Specific to:

Honda CR-V 2007-2008

Special tool required:



O2 sensor wrench, Snap-On® S3176, or equivalent
 


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 before removing the sensor from the exhaust system.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the secondary HO2S 4P connector (A).
  4.  
  5. Remove the secondary HO2S (B).
  6.  

To install:

  1. Install the secondary HO2S (B) and tighten to 33 ft. lbs. (44 Nm).
  2.  
  3. Connect the secondary HO2S 4P connector (A).

    Click image to see an enlarged view

    Fig. Removing the Heated Oxygen (HO2S) Sensor 2

  4.  

Testing



Specific to:

Honda CR-V 2007-2008

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Perform a visual inspection of the sensor as follows:
    1. If the sensor tip has a black/sooty deposit, this may indicate a rich fuel mixture.
    2.  
    3. If the sensor tip has a white, gritty deposit, this may indicate an internal coolant leak.
    4.  
    5. If the sensor tip has a brown deposit, this could indicate oil consumption.
    6.  

  4.  
  5. Check that the output voltage, in the rich/lean readings, fluctuate according to specifications using the Honda Diagnostics System (HDS), or equivalent scan tool.
  6.  
  7. Check the HO2S SENSOR in the DATA LIST.
  8.  
  9. Start the engine and allow it to come to operating temperature.
  10.  
  11. If voltage is not within specification, inspect the connectors and wiring harness.
  12.  
  13. If no faults are found, replace the sensor.
  14.  

 
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