Fuel filter

An engine system comprising:

• an internal combustion engine;
• and
• a fuel supply system configured to supply fuel to the internal combustion engine, the fuel supply system having:
• a fuel tank;
• a fuel pump;
• a fuel filter including:
• a filter housing, which has an untreated-side inlet, a treated-side outlet and an untreated-side return line;
• a filter element which is arranged in the filter housing, the filter element including an untreated space and a treated space, and which separates in the filter housing the untreated space communicating with an inlet and the return line from the treated space communicating with the outlet;
• a closure element, which in an operationally ready state of the fuel filter closes-off the return line;
• and
• a pressure sensor configured to measure a pressure build-up in the treated space, wherein the fuel filter is configured to enable the pressure build-up to reach a predetermined threshold at which the engine is started;
• and
• an engine control device configured to monitor the pressure build-up in the treated space, and to generate a start signal for starting the internal combustion engine when the pressure-build up reaches the predetermined threshold.