Lambda Sensors Catalogue

ϒ
Lucas Lambda Sensors
Lucas Technical tips
Lambda sensors, unlike other types of sensor fitted to an engine, have an optimum performance life cycle,
which generally lasts about 45 000 to 60 000 thousand miles. The decrease in performance happens gradually
to a point where the sensor will become tired or lazy. The sensor still works but the reaction times are slow.
Regular drivers of the vehicle will not notice this change.
Testing a Zirconia Lambda sensor off the vehicle is quite easy, all you need is a vice or a similar means of
holding the sensor, a propane torch and a high impedance digital multimeter.
Test using a four wire Zirconia sensor
WARNING
When using propane
torches remember to
read and follow the
manufacturers safety
instructions
First check the general condition of the sensor if there is any sign of damage change the sensor. Now test
the heater circuit for continuity, if the heater has failed change the sensor. now connect the voltmeter red probe
to the signal wire (generally black) and the black probe to the earth (generally grey) and set voltmeter to .000
volts. Then with a propane torch heat up the tip of the sensor until it is cherry red. The sensor should give off
a reading of nearly 1 volt in a few seconds. If it takes longer than 20 seconds to get a reasonable reading change
the sensor. In the case of a 1 or 3 wire sensor the body of the sensor is the earth. (For wire colours see chart).
There is only one test you can do on a Titania Lambda sensor off the vehicle and that is to test the heater
circuit for continuity. The best way to test these sensors is on the car with an oscilloscope. The signal should
switch between 0-1 volt and 0-5 volt, depending on the range of the sensor.
One of the most misdiagnosed reasons for changing a Lambda sensor is when the vehicle fails an MOT on
the emission test when the Lambda reading ( ) is high. This is not a measurement of the Lambda sensor but
a calculation of the burn. High Lambda in this case is too much oxygen in the exhaust system; usually a pinhole
in the exhaust after the Lambda sensor. Check if the exhaust is in good condition or has had any part replaced
recently, and this will be the most likelly cause, not the Lambda sensor.
9