Lambda probe

Lambda probe (oxygen sensor, or O₂ -sensor) installed in front of the catalytic converter. The ceramic sensor head is externally in the exhaust gas flow and internally connected to the outside air. Due to the difference in the oxygen content in the exhaust gas and in the air, a voltage is generated in the sensor, which increases sharply at a certain residual oxygen content in the exhaust gas. With a lack of oxygen, i.e. rich combustible mixture, the voltage is 800–1000 mV. In the presence of a poor combustible mixture, it can reach a level of 100 mV.

The voltage signals generated by the lambda probe are transmitted to the fuel mixture preparation control unit, which, based on these data, starts the lambda control process, which maintains the air-fuel ratio at the required level.

The lambda probe reacts to oxygen fluctuations depending on its operating temperature in different ways: at 300°C, this happens within 1 s, at 60°C - already in 50 ms. Thanks to the built-in heating element, the most optimal temperature of 60°C can be reached fairly quickly. In addition, the sensor must be located as far as possible from the engine so that even with prolonged full load it will not be damaged due to engine overheating.