2026-09-15
Lexus IS 250/300h/350 Thermostat Replacement Malaysia
A faulty thermostat causes either overheating (stuck closed) or the engine never reaching operating temperature (stuck open), which increases fuel consumption and wear. The IS thermostat opens at 82°C. Replacement costs including parts and labour — always replace the gasket and refill with the correct Toyota SLLC coolant. Combine with a coolant flush for maximum value.
Lexus IS Thermostat
- IS thermostat: wax-element thermostat — opens at ~80°C; replace at 100,000 km or if temperature gauge runs consistently low (stuck open) or overheats (stuck closed)
- Thermostat housing: plastic housing on some IS engines — inspect for hairline cracks at 80,000 km; replace housing when replacing thermostat
- IS 300h thermostat: Atkinson cycle engine runs cooler — thermostat opens earlier; normal operating temp is slightly lower than IS 250/350
- Always replace with genuine Toyota/Lexus thermostat — aftermarket thermostats open at incorrect temps, causing rich running or overheating