How they work

Lambda Sensors work together with the vehicle’s fuel injection system, Catalytic Converter and engine management system or electronic control unit (ECU) (Fig. 1) to help achieve the lowest possible output of environmentally harmful engine emissions:

  • The Lambda Sensor monitors the percentage of unburned oxygen present in the car’s exhaust gases.
  • According to whether the oxygen content in the exhaust gas is too high (a lean mixture) or too low (a rich mixture) the Lambda Sensor transmits a fast-changing, fluctuating voltage signal to the ECU.
  • The ECU responds to this information by adjusting the air/fuel mixture entering the Catalytic Converter. The goal is to keep the air/fuel ratio very close to the ‘stoichiometric’ point, which is the calculated ideal ratio of air to fuel entering the Catalytic Converter.

Theoretically, at this ratio, all of the fuel will be burned using almost all of the oxygen in the air. The remaining oxygen must be exactly the right quantity for the Catalytic Converter to function efficiently.

Watch this short animation to understand DENSO Lambda Sensor technology: