Who makes automotive thermostats?
Automotive thermostats are produced by a small group of global suppliers that design and manufacture the cooling-system valves used across cars, trucks and SUVs. The leading names include Stant, Mahle Behr, Bosch, Denso, Valeo and BorgWarner, among others. These components are typically sold as standalone units or as part of cooling modules to automakers and the aftermarket.
Global manufacturers and their role
The following companies represent the core players in the automotive thermostat market. They provide either standalone thermostats or thermostat assemblies that integrate with housings, sensors and control valves for OEMs and, in many cases, for aftermarket channels.
- Stant Manufacturing (United States) — a long‑standing specialist focused on thermostats, radiator caps and related cooling components; active in both OEM supply and the aftermarket.
- Mahle Behr (Germany) — the cooling-system arm of the Mahle Group, supplying thermostats, thermostatic modules and complete cooling assemblies to many automakers.
- Bosch (Germany) — a broad automotive supplier that offers thermostats as part of its cooling-system products and modules for numerous brands.
- Denso (Japan) — a major global Tier 1 supplier producing thermostat units and integrated cooling solutions for a wide range of automakers.
- Valeo (France) — a leading thermal-management supplier providing thermostats and cooling-module solutions to European and global OEMs.
- BorgWarner (United States) — offers thermal-management components, including thermostat assemblies and related cooling-system solutions, to various manufacturers.
Automakers typically source thermostats from these global suppliers, either as standalone parts or as part of integrated cooling modules that combine the valve, housing, sensors and control features into a single unit. The exact supplier can vary by brand, region and vehicle platform, and many automakers use the same supplier across multiple models.
How the market works
Most thermostats are developed within broader cooling-system programs. OEMs collaborate with Tier 1 suppliers during vehicle development to ensure compatibility with engine timing, ambient conditions and emission requirements. Aftermarket consumers seeking replacements often rely on the same manufacturers through authorized distributors, though there are regionally specialized suppliers as well.
Because thermostats are small, high-precision components, supply chains emphasize reliability, precise temperature thresholds, and rapid response to changing engine operating conditions. As vehicles adopt more advanced thermal-management strategies, some thermostats are deployed as part of modular cooling units that include sensors, actuators and electronic control interfaces.
Summary
In today’s automotive market, a handful of global manufacturers dominate thermostat production: Stant, Mahle Behr, Bosch, Denso, Valeo and BorgWarner lead the way with standalone units and modular cooling solutions. These players serve both original equipment manufacturers and the aftermarket, with the trend toward integrated cooling modules that streamline production and improve thermal control across diverse vehicle platforms.
