Tire pressure sensor for motor vehicles

In a tire pressure sensor for motor vehicles, comprising a pressure switch for monitoring tire pressure, said pressure switch being fastened at a circumference of a wheel rim and being actuated by the tire pressure, said pressure switch including a reference pressure chamber;

• a diaphragm, said reference pressure chamber being closed in the direction of the tire by said diaphragm which is electrically conductive;
• an element enclosing said reference pressure chamber;
• a contact pin supported in said element and engageable with a middle area of the diaphragm for closing an electric circuit when there is sufficient air pressure in the tire;
• the improvement comprising an air gap (X) provided between the contact pin (30) and the middle area of the diaphragm (29) for testing leakage of the reference pressure chamber (21a) when an equal pressure occurs on both sides of the diaphragm (29), the element enclosing the reference pressure chamber being fastened in a sensor housing (16), which is fixed in the wheel rim (12) and closed toward outside, in such a manner that it is surrounded by the compressed air in the tire (11).