Thermostat 21200AA072 (WRX MY99-14/STI MY01-17)

Keep your cool under pressure.

This genuine Subaru thermostat is the heart of your cooling system—controlling coolant flow to maintain optimal engine temp. Whether you're chasing boost or just daily duties, a healthy thermostat is essential for consistent performance and long-term reliability.

If you're seeing fluctuating temps or your warm-up time's all over the place, it might be time for a refresh.

✅ Genuine Subaru quality
✅ Opens at 78°C
✅ Direct fit for WRX (1999–2014) & STI (2001–2017)
✅ Restores correct coolant flow and warm-up times

Pair it with a fresh gasket and radiator cap for a full cooling system refresh. Roo Racing recommends this part for any service, rebuild, or peace-of-mind maintenance.

Our suppliers have awesome connections and coverage of the Subaru parts catalogue, we're opening this to you on a back order basis. Orders for genuine and aftermarket maintenance parts are submitted twice each month and very little stock is actually kept on hand, so please be prepared for a 3-4 week turn around on maintenance parts orders.