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Switches & Sensors

Lambda Sensor (Oxygen Sensor)

 
  • Monitors the oxygen content of exhaust gas to help maintain the correct air/fuel ratio
  • Ensures the catalytic converter is operating at maximum efficiency

Troubleshooting:

  • Symptoms:
    • Irregular idling
    • Loss of engine power
  • Possible causes for failure:
    • Element damaged due to exhaust gas heat
    • Vibration from exhaust damaging wire connectors

Testing:

Before inspecting the part, make sure that the exhaust is cool. The Lambda sensor operates in extremely high temperatures so damage to the heater element of the sensor is the most frequent fault associated with this part.

  1. Disconnect the sensor from the electrical connector and test the resistance of the part using a multimeter. You will need to use both heater wires for this test. Note: these wires are commonly white. If the resistance is between 1 and 20 ohm it would suggest the part is working correctly.
  1. If the sensor is showing a reading between 1 and 20 ohm but the problems persist, the sensor itself may be registering incorrect readings.
  1.  This must be tested under normal driving conditions with the sensor connected to a voltmeter. This will test how quickly the sensor reacts to changing conditions.
  1.  To do this, find a way of allowing extra air into the intake while the engine is running. The easiest way of doing this is to remove the brake servo hose.

The next step is to make the fuel mixture rich; this can be done by restricting the airflow into the manifold.

It is important that this is only blocked while the engine is idling as the pressure during acceleration may be strong enough to remove any blockages. By doing this the sensor voltage should react to change quickly, if it does not change instantly this suggests the sensor is sluggish; the reading should fall to zero and work its way back up slowly.

  1. If it appears that the sensor is working correctly check electrical connections for voltage using a multimeter and all surrounding wires for damage.

Common Fault Codes

  • P0131 02 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
  • P0134 02 Sensor Circuit No Activity

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