Parts for your 2020 Toyota Vitz|yaris-Thermostat

2020 Toyota Vitz / Yaris Thermostat — What it does and when to replace it

Yes, the 2020 Toyota Vitz/Yaris uses a coolant thermostat. This isn’t an optional extra — it’s a standard cooling-system component on both the late XP130 Vitz/Yaris (1KR-FE, 1NR-FE, 2NR-FKE and hybrid 1NZ-FXE) and the 2020-on Yaris (M15A engines) sold in AU/NZ. Toyota’s Technical Information System (TIS) service manuals include specific removal/installation and inspection procedures for the thermostat on these models, and Toyota’s Electronic Parts Catalog (EPC) lists the thermostat within the Water Outlet/Thermostat assemblies for KSP/NSP/NHP130 and XP210 series vehicles.

On this car, the thermostat’s job is simple but crucial: it helps the engine warm up quickly, then keeps coolant temperature steady by opening and closing as needed. Faster warm-up means better fuel economy, lower emissions, and consistent heater performance on cold starts. Once at temp, a healthy thermostat keeps the gauge rock-solid and prevents overcooling on the open road.

While Toyota doesn’t set a fixed replacement interval, a thermostat is a wear item. It’s smart to inspect or replace it proactively when:

• Doing a coolant change, water pump, or timing/cooling system work
• The heater’s lukewarm, fuel use has crept up, or the gauge hangs low (stuck open)
• The engine overheats or the upper hose stays cold too long (stuck closed)
• You’ve had any major overheat event

For the 2020 Yaris in Australia and New Zealand (M15A engines), the thermostat is typically housed in the water inlet/outlet assembly with an O-ring seal. The earlier Vitz/Yaris engines are similar — a wax-pellet type thermostat in the housing. Always use a genuine or high-quality OEM-spec unit and a new gasket/O-ring. Don’t smear silicone around it