A heating device for heating fuel in a vehicle comprises a body having an inlet and an outlet. Arranged inside the body are electrical heating means (11) in contact with the fluid, means (IP) for controlling the electrical supply of the heating means (11),...

On each use of the system, a sensor (2) downstream of the filter (1) measures the air velocity (21). This is compared with a reference air velocity from the non-laden (i.e. new) filter. The result is transmitted to a service computer or display. Should the...

Differential pressure measuring arrangement (10) comprises an evaluating unit (19) for determining the differential pressures which are lower than the lowest reference pressure value. The lowest reference pressure value is lower than the differential press...