Mazda notes that some vehicles may experience the aluminum valve stem breaking off of the TPMS sensor when removing aftermarket valve stem caps.
Some aftermarket valve stem caps are made of brass or have brass thread inserts. When brass and aluminum are together, galvanic corrosion occurs between the aluminum valve stem of the TPMS sensor and the brass threads of the cap. This corrosion can cause them to fuse together, becoming difficult to remove by hand. When more force is used to remove the valve stem cap, the aluminum valve stem will break off and the TPMS sensor must be replaced.
Advise customers to use plastic or aluminum valve stem caps only, and to make sure that valve stems caps do not feature brass threads.