The lambda control circuit

The control sensor measures the remaining oxygen in the still unprocessed exhaust. In the process, a sensor signal arises which the engine control unit (also "ECU") uses in order to change the mixture composition.

The diagnostic sensor measures the remaining oxygen in the processed exhaust. On the basis of its signal, the engine control unit can recognise exhaust-relevant malfunctions and report them to the driver.

The lambda sensor upstream of the catalytic converter is a regulating sensor which measures the residual oxygen in the exhaust gas and sends a signal to the engine controller. The voltage at the sensor varies depending on the oxygen concentration in the ex
Lambda sensors and the engine control unit form a closed loop control system

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