Abstract: A fuel filter assembly for diesel fuel includes a filter head structure, spin-on replaceable element and threaded collection bowl. An annular heater housing is secured in the filter head for warming the fuel prior to passage through the filter medium with a pair of positive temperature coefficient heater discs providing the self-regulating heater function. A check valve is housed in the inlet chamber of the filter head in bypass connection with the filter medium to vent air from the chamber and to establish a return path for fuel from the filter. A restrictive orifice in the check valve limits fuel flow in the bypass path and an elastomeric duck-bill type valve provides the check valve function.