Lambda sensor, also known as oxygen (O2) sensor, is a sensor located in the exhaust system of internal combustion engines and measures the amount of oxygen in the exhaust gases. This sensor provides the engine control unit (ECU) with the information necessary to set the correct air-fuel mixture. The lambda sensor is found in both gasoline and diesel engines and plays a critical role in reducing emissions and improving fuel efficiency.
The main function of the lambda sensor is to provide feedback to the engine control unit (ECU) by measuring the oxygen level in the exhaust gases. This information ensures that the engine's air-fuel mixture remains in optimal proportions.
Adjusting the Air-Fuel Mixture: The ideal air-fuel mixture ratio (stoichiometric ratio) is generally 14.7:1 (14.7 parts air, 1 part fuel). The lambda sensor provides information to the ECU to maintain this ratio.
The lambda sensor contains a ceramic sensor element. This element comes into contact with exhaust gases on one side and atmospheric air on the other.
Electrochemical Reaction: Oxygen ions create an electrochemical reaction on the surface of the sensor element, and as a result of this reaction, an electrical voltage is produced. This voltage varies depending on the amount of oxygen in the exhaust gases.
Feedback: The ECU adjusts the air-fuel mixture using this voltage signal. If the oxygen level is low (rich mixture), fuel injection is reduced. If the oxygen level is high (lean mixture), fuel injection is increased.
