Fuel heater with bimetal

Fuel heater comprising a housing (2) surrounding a through-flow of the to be heated fuel flow channel (5), in which an electric heating element is arranged at least, and a bimetal switch (4) to a current flowing through the heating element when reaching a switching temperature to interrupt, the bimetal switch (4) on the housing (2) is fixed in a position in which it is exposed to the diesel fuel, and wherein the bimetal (4) (4a, 4b) comprises a sealed switch housing, characterized in that the bimetal switch (4) outside the flow channel (5) is arranged in a flow-impeding of diesel fuel capable and causes the housing (2), that part of the fuel flow is diverted and as a bypass current to the bimetal switch (4) is flowing past while the largest part of the fuel material flow through the flow channel (5) flows.