BorgWarner Inc WT358 Coolant Temperature Switch

The BorgWarner WT358 coolant temperature switch is a thermostatic switch used in automotive cooling systems to monitor engine coolant temperature and actuate an electrical circuit—typically to drive a cooling fan or to provide a temperature signal to the vehicle’s control systems—when the coolant reaches a predetermined threshold. In aftermarket catalogs, WT358 is listed under the BWD Automotive line as an engine coolant temperature switch/sensor pair and is often cross-referenced with identifiers such as SK3935 and DS149 B2, reflecting its use as a direct, replaceable component in various OEM and aftermarket coolant circuits. Some listings indicate a mounting thread of 1/2 inch with 18 threads per inch for the WT358, though exact thread specifications can vary by vehicle and year; buyers should confirm thread size and port type against their engine’s service manual or the part’s catalog data to ensure proper fit. Because compatibility for a specific vehicle is not universal across all BorgWarner/BWD WT358 applications, verify the part number against your engine’s requirements and consult the supplier’s fitment notes before purchasing.