An exhaust treatment system may include a burner, a flame sensor assembly and a control module. The flame sensor assembly may be at least partially disposed within the burner and may include an insulator and an electric heating element in heat transfer relation with the insulator. The control module may be in communication with the flame sensor assembly. The control module may determine whether a flame is present in a combustion chamber based on feedback from the flame sensor assembly. The control module may detect contamination on the insulator based on feedback from the flame sensor assembly. The control module may operate the heating element in a first mode in response to detection of a contamination in which the control module causes electrical power to be applied to the heating element to raise a temperature of the heating element to burn contamination off of the insulator.