A defective thermostat can result in engine overheating and potential internal damage. Improve the reliability of your 2003+ Toyota 4Runner 4.0L cooling system with a Mishimoto Low-Temperature Racing Thermostat and housing! This thermostat is designed as a direct-fit replacement for your aged stock unit. The Mishimoto thermostat has a lower activation temperature (71?C/160?F) compared to the factory thermostat (82?C/180?F). The lower activation temperature allows coolant to flow through the engine earlier, which reduces and maintains lower engine temperatures. This thermostat is ideal for use in warmer climates, on vehicles making more power than stock, or under extreme towing/driving conditions. The stock-style housing will provide a proper seal and installs easily. Like all our Toyota Performance parts, this thermostat and housing includes the Mishimoto Lifetime Warranty. This Part Fits: Year Make Model Submodel 2003-2021 Toyota 4Runner Limited 2003-2009 Toyota 4Runner Sport 2003-2021 Toyota 4Runner SR5 2018-2021 Toyota 4Runner SR5 Premium 2010-2016,2021 Toyota 4Runner Trail 2017-2021 Toyota 4Runner TRD Off-Road 2015-2021 Toyota 4Runner TRD Pro 2007-2014 Toyota FJ Cruiser Base 2008 Toyota FJ Cruiser Trail Teams Special Edition 2007 Toyota FJ Cruiser TRD Special Edition 2005-2008 Toyota Tacoma Base 2005-2008 Toyota Tacoma Pre Runner 2005-2008 Toyota Tacoma X-Runner