AISIN Engine Coolant Thermostat with Housing THT-017 for Lexus CT200h & Toyota Prius/Corolla — OE-fit, Pre-assembled

AISIN GENUINE THT-017 is a direct-fit engine coolant thermostat with housing engineered to restore proper engine temperature control for select Lexus CT200h and Toyota Prius/Corolla models.

This OEM-matched thermostat assembly replaces the original unit to help the cooling system operate within the manufacturer’s specified temperature range. Built by AISIN with OE-level materials and manufacturing, the THT-017 is designed for correct form, fit, and function so installation is straightforward and the part performs consistently over time. The kit arrives with the thermostat pre-mounted in its housing, simplifying replacement and reducing the chance of installation issues.

How does this thermostat affect vehicle temperature regulation?

The thermostat controls when coolant circulates between the engine and radiator, helping the engine reach and maintain its designed operating temperature. A properly functioning AISIN THT-017 opens at the OE-specified temperature to allow coolant flow and closes when the engine cools, supporting efficient warm-up and steady running conditions. Using an OE-matched component reduces the risk of out-of-spec behavior that can cause overcooling or overheating.

• Opens at the manufacturer-specified temperature for accurate thermal control
• OE-form housing ensures correct coolant routing and sealing
• Pre-assembled unit shortens install time and lowers leak risk

What vehicles and engines is the THT-017 compatible with?

This AISIN thermostat assembly fits a range of hybrid and gasoline applications from Lexus and Toyota, but exact compatibility can vary by engine and model year. Common fits include Lexus CT200h and multiple Prius variants, as well as select Corolla model years. Always verify fitment using your vehicle VIN or the seller’s fitment checker before ordering to confirm engine-specific compatibility.

• Lexus CT200h: 2011–2017 (verify engine code and VIN)
• Toyota Corolla: select 2020–2022 models (confirm fitment)
• Toyota Prius family: 2010–2022 Prius, 2019–2022 Prius AWD-e, 2012–2015 Prius Plug-In, 2017–2022 Prius Prime, 2012–2018 Prius V

Why choose an AISIN OE-matched thermostat instead of an aftermarket generic part?

AISIN supplies original-equipment technologies and manufacturing processes, so their thermostat matches the original part’s dimensions, operating temperature, and mounting points. That makes installation simpler and reduces the chance of fitment or performance issues that can arise with non-matched aftermarket parts. The use of high-quality materials aims to deliver longevity and consistent performance under normal operating conditions.

• OE-specified operating temperature for predictable engine warm-up
• Correct housing geometry for reliable sealing and coolant flow
• Manufactured to automotive-grade standards for durability

What should I expect during installation and maintenance?

Installation typically involves draining part of the cooling system, removing the old thermostat housing, swapping the assembly, and refilling the coolant to the proper level. Since the thermostat comes with its housing, gasket surfaces and fastener locations match the OE, which reduces extra adjustments. After installation, monitor coolant level and engine temperature during the initial warm-up and road test to ensure there are no leaks and the thermostat opens at the correct time.

• Pre-assembled thermostat and housing for simplified replacement
• Gasket or seal seating per OE specifications—follow torque values
• Check coolant level and bleed air from the system after replacement

Who is this for: The AISIN THT-017 thermostat with housing is intended for owners and technicians who need an OE-matched replacement for select Lexus CT200h and Toyota Prius/Corolla models. It’s a suitable choice for routine replacement, cooling system repairs, or when restoring proper engine temperature control after a failing thermostat. Confirm vehicle and engine fitment before purchase to ensure correct application.