For 1990-2009 cars

1. Inspect the linings when you remove the wheels and during routine maintenance. Refer to Maintenance Schedule - Short Trip/City and to Maintenance Schedule - Long Trip/Highway in Maintenance and Lubrication.
2. Inspect both ends of the outer pad (3) by looking through the lining inspection hole (1) in the caliper. These are the points where the highest rate of wear normally occurs. At the same time, inspect the thickness of the inner pad (3) in order to ensure that the pad has not worn prematurely. Replace the pad if the minimum thickness is less than 1 mm (0.04 in).