A tire pressure monitoring system sensor includes a body provided with an air inlet that provides fluid communication between the interior of the body and the interior of a tire. A pressure plate slides within the interior of the body by pressure in the tire, in a direction away from the air inlet. A spring biases the pressure plate toward the air inlet. Several sensors are attached to the body, each configured to generate a signal indicative of proximity of the pressure plate. The sensor may further include an air supply valve to supply air to the tire, connected to the body. The body may define an air supply passage through which the air supplied from the air supply valve is supplied to the tire through the air inlet. Three sensors may be provided: one indicative of excessive pressure, one indicative of appropriate pressure, and one indicative of insufficient pressure.