In at least one embodiment, the present invention relates to a tire pressure monitor system located within the interior of a tire. The system comprises a housing having a wall forming a cavity and an interior wall forming an opening in fluid communication with the cavity, a tire pressure sensor located within the housing cavity, and a pressure cap inserted into the housing opening. The tire pressure sensor has an orifice for helping to sense tire pressure. The pressure cap comprises a wall having a portion that contacts the sensor and extends around the sensor orifice.