A pressure sensor (20) includes a test cell (32) and sense cell (34). The sense cell (34) includes an electrode (42) formed on a substrate (30) and a sense diaphragm (68) spaced apart from the electrode (42) to produce a sense cavity (64). The test cell (32) includes an electrode (40) formed on the substrate (30) and a test diaphragm (70) spaced apart from the electrode (40) to produce a test cavity (66). Both of the cells (32, 34) are sensitive to pressure (36). However, a critical dimension (76) of the sense diaphragm (68) is less than a critical dimension (80) of the test diaphragm (70) so that the test cell (32) has greater sensitivity (142) to pressure (36) than the sense cell (34). Parameters (100) measured at the test cell (32) are utilized to estimate a sensitivity (138) of the sense cell (34).