Fuel filters can also contain additional features such as fuel heaters, thermal diverter valves, de-aerators, water-in-fuel sensors, filter change indicators.

A fuel preheater helps minimize the accumulation of wax crystals that can form in the fuel as it cools to low temperatures. Common heating methods use electric heaters, engine coolant or recirculated fuel. Two approaches that use warm return fuel to heat the incoming fuel are shown in Figure 1.

Fuel overflow and leak-off fuel returning to the tank also carries air and fuel vapor. The presence of gaseous substances in the fuel can cause difficulties in starting as well as normal engine operation in high temperature environments. Therefore, bleeder valves and de-aerators are used to rid the fuel supply of vapors and air to ensure trouble-free engine operation.