Method of operating a diesel fuel filter of a vehicle engine and filter device

摘要

The method involves using a filter and a unit to display a maintenance signal when the filter is to dirty. The maintenance signal is generated according to the fuel state on the input side of the filter, when both the fuel temperature and pressure are above specified threshold values. A heating unit (1) may be connected to the input side of the filter, when the fuel temperature is below the threshold but the fuel pressure is above the threshold. Independent claims are included for a filter unit and for a unit with a heater for the vehicle engine.