Caliper Inspection: Piston
WARNING: This page is about a different car, the 2011 Nissan Xterra. However, it is still accessible from the selected car via links, so may be relevant.
Check the piston for score, rust, wear, damage or presence of foreign materials. Replace if any of the above conditions are observed.
CAUTION:
Piston sliding surface is plated, do not polish with emery paper even if rust or foreign materials are stuck to sliding surface.