Test OXYGEN Sensor and ECU in 5 MINUTES

To test the oxygen sensor or LAMBDA probe, the multimeter can be used to measure the operating voltages.
In the first oxygen sensor test we measure the voltage generated by the oxygen sensor as it is heated by the extremely hot gases coming out of the exhaust pipe.
As the oxygen sensor becomes hotter, exceeding 200 degrees Celsius, it begins to generate a small voltage that can be easily measured with a multimeter on the 2 Volt DC scale.
To test that the car's computer (ECU: Electronic Control Unit) works correctly with the oxygen sensor, we proceed as follows:
We disconnect the oxygen sensor, put the ignition switch in the contact position and measure the voltage present in the oxygen sensor connector that comes from the ECU, it should give a value of about 335 mV.
Then we connect the oxygen sensor in its place, we connect the leads of the multimeter to the oxygen sensor, we turn on the engine and we must observe that the voltage starts from the 335 mV that we measured at rest.
Once the oxygen sensor begins to warm up then the voltage of 335 mV begins to vary, we can accelerate the engine to notice that the voltage goes up and down.