Galvanic corrosion occurs when dissimilar conducting materials, such as brass and aluminum, are in contact with each other electrically and exposed to an electrolyte. The galvanic corrosion reaction will cause one or more of the dissimilar materials to corrode. In the case of TPMS, if a brass valve core is installed into an aluminum stem or a brass cap is installed onto an aluminum stem, galvanic corrosion will occur and cause the two dissimilar metals to fuse to one another, resulting in damage to the stem, core and cap. Galvanic corrosion can damage the TPMS sensor beyond repair and will necessitate replacement of the sensor. Your tire service center will ensure that your TPMS system is properly serviced when you take your vehicle in for repair.