Abstract: Temperature sensor in plug form comprises a plastic body member having a bore with a metallic sensing member in one end, a thermistor in the bore, and a contact member with a spring portion in the bore and a contact portion extending through a slot in the body member from the bore to the other end of the body. Contact portion has electrical terminal for wire attachment and spring portion maintains contact with thermistor. Sensing member has retaining arms which extend into grooves in threaded cylindrical surface of body which are threaded as body is screwed into place in an engine block.