Keep coolant moving at the right temperature with the AISIN Engine Coolant Thermostat & Housing Assembly (THT-021). It drops in as a direct-fit replacement for the 2016-2022 Lexus RX450H, 2018-2022 Lexus RX450HL, 2025 Lexus TX550H+, and 2017-2019 Toyota Highlander, all with the V6-3.5L engine.
A coolant thermostat regulates the flow of coolant between the engine and radiator, staying closed during warm-up and opening as the engine reaches operating temperature to help hold coolant within its intended range. This assembly combines the thermostat with its housing for a complete swap.
- OE engineered and manufactured: built for exact form, fit, and function as a direct replacement.
- Exact temperature: calibrated to open at the specified temperature to maintain cooling system performance.
- Temperature management: designed to keep coolant within the optimal temperature range.
- Country of origin: Japan.
Signs the original thermostat may need replacing include overheating, slow warm-up, a temperature gauge that runs low or erratically, or coolant seepage at the housing. Diagnose the cause before replacing, since these symptoms can have other sources.
Interchange: 1601-684289 · 143-0953 · 905-5212 · 1040-180 · 16031-31040
1601684289 · 1430953 · 9055212 · 1040180 · 1603131040 · 86321
This part cross-references / interchanges with the following part numbers:
1601-684289, 143-0953, 905-5212, 86321, 1040-180, THT-021, 16031-31040
