Fuel filter heating system (BMW 7 Series E32)

When the ambient temperature drops, the fluidity of diesel fuel decreases due to the concentration of paraffin. Diesel fuel becomes viscous, like honey. For this reason, companies producing diesel fuel add additives to winter fuel, which increase the fluidity of the fuel and ensure reliable engine starting down to minus 15°C (some grades - down to minus 22°C).

However, these additives are not always available for reliable engine operation in winter. For this reason, the fuel filter is equipped with an electric heater. Thanks to this, thickening of diesel fuel is prevented even in severe frost.