The transmission in your 2012-2018 Jeep Wrangler JK is the heart of its drivetrain. Whether you're hauling groceries or hitting the trail, it's vital to keep it performing at its best, and keeping the transmission fluid cool is crucial to that goal. In an attempt to balance driveability and the health of your transmission, Jeep fitted a thermostatic bypass valve to the lines that feed the transmission cooler. This valve ensures fluid doesn't flow through the cooler before the transmission reaches operating temperature, preventing overcooling in cold environments. However, when the thermostat in this valve fails, it's almost a guarantee your transmission will overheat. Moreover, those who live in hot climates will likely never have to worry about overcooling, rendering the valve a useless flow restriction. That's why Mishimoto has developed a performance thermostatic bypass valve for the 2012-2018 Jeep Wrangler JK. Our performance thermostatic bypass valve features a fully-serviceable and removable thermostat. For those who live in hot climates, the thermostat can be replaced with the included bypass to allow full flow to the transmission cooler at all times. Speaking of flow, the Mishimoto performance thermostatic bypass provides increased flow over the stock valve to ensure your transmission cooler operates at peak efficiency, even with the thermostat installed. The included thermostat opens at the stock temperature of 160°F (71°C), but the valve can be customized to suit your needs with any available Mishimoto thermostat. The Mishimoto performance thermostatic bypass valve is a direct-fit and is made from durable aircraft-grade aluminum that's anodized to withstand even the harshest environments. Like all of our Jeep products, our performance thermostatic bypass valve is backed by our Mishimoto Lifetime Warranty.