Functional description

The ethanol sensor measures the ethanol content and temperature of the fuel. The dielectric conductivity (= conductivity of a material regarding electrical fields) as well as the electrical conductivity and temperature are determined to achieve a result. After the ethanol content has been calculated, it and the temperature are communicated to the engine management ECU by means of a PWM signal.

2 electrodes form a sensor cell that detects the dielectric conductivity when a current is applied.

Fig 1: Ethanol Sensor And Three Pin Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.