Lambda probe (Mondeo 2)

The lambda probe (oxygen sensor, or O ₂ sensor) is installed before the catalytic converter. The ceramic head of the sensor is located outside in the exhaust gas flow and is connected to the outside air from the inside. Due to the difference in 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. a rich combustible mixture, the voltage is 800-1000 mV. With a lean combustible mixture, it can reach 100 mV.

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

The lambda probe reacts to oxygen fluctuations differently depending on its operating temperature: 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 quite quickly. In addition, the sensor should be located as far away from the engine as possible so that even with prolonged full load, damage does not occur due to engine overheating.