Abstract: The disclosure relates to a method for determining a level of a liquid in a tank with an ultrasonic fill state sensor and at least two reference surfaces for reflecting an ultrasonic wave transmitted by the ultrasonic fill state sensor. A first reference surface is arranged below a second reference surface. The method includes determining a first propagation speed of an ultrasonic wave to the first reference surface on a first measurement path and a second propagation speed from the first reference surface to the second reference surface on a second measurement path. The method also includes measuring a propagation time of an ultrasonic wave from the ultrasonic fill state sensor to a liquid level of the liquid in the tank, selecting the first propagation speed or the second propagation speed based on at least one selection criterion, and calculating a fill state using the propagation time measured.

Abstract: A method for determining a liquid level in a tank of a vehicle uses an ultrasonic sensor for emitting and receiving ultrasonic waves. Basically the liquid level is determined based upon measuring the transition time of an ultrasonic wave emitted by the ultrasonic sensor, wherein the emitted wave is deflected two times before being reflected by the surface of the liquid contained in the tank.

Abstract: The invention relates to a method for determining a liquid level in a tank (1) comprised in a vehicle, wherein said method uses an ultrasonic sensor (4) for emitting and receiving ultrasonic waves (11). Basically the liquid level is determined based upon measuring the transition time of an ultrasonic wave (11) emitted by the ultrasonic sensor, wherein said emitted wave is deflected two times before being reflected by the surface (2) of the liquid contained in the tank.

Abstract: The invention relates to a heater for a device for providing a liquid additive in a motor vehicle, comprising at least one switchable resistance heating element, which is connected in series with at least one switch element, by means of which the at least one resistance heating element can be activated and deactivated, and comprising at least one permanent resistance heating element, which is connected in parallel with the at least one switchable resistance heating element and the at least one switch element.

Abstract: The disclosure relates to a method for determining a level of a liquid in a tank with an ultrasonic fill state sensor and at least two reference surfaces for reflecting an ultrasonic wave transmitted by the ultrasonic fill state sensor. A first reference surface is arranged below a second reference surface. The method includes determining a first propagation speed of an ultrasonic wave to the first reference surface on a first measurement path and a second propagation speed from the first reference surface to the second reference surface on a second measurement path. The method also includes measuring a propagation time of an ultrasonic wave from the ultrasonic fill state sensor to a liquid level of the liquid in the tank, selecting the first propagation speed or the second propagation speed based on at least one selection criterion, and calculating a fill state using the propagation time measured.