Parts for your 2010 Subaru Exiga-Thermostat

2010 Subaru Exiga Thermostat — What It Does and When to Replace It

Based on Subaru factory service information and the genuine parts catalogue for the 2010 Subaru Exiga (EJ20-series flat-four, both naturally aspirated and turbo), this vehicle is fitted with a conventional wax‑pellet engine thermostat. It’s a standard, critical component of the Exiga’s liquid cooling system, mounted in the thermostat housing at the front of the engine near the water pump/lower radiator hose. So yes—the thermostat is absolutely relevant and used on the 2010 Subaru Exiga.

The thermostat’s job is to help the engine warm up quickly, then hold it at the sweet spot for efficiency and longevity. When the motor is cold, the thermostat stays shut so coolant circulates within the engine only, bringing temperatures up faster for better fuel economy, smoother running, proper heater performance, and lower emissions. Once it reaches its target range (typically around the low‑80s °C for many Subaru units—always check the spec listed for the specific engine), it opens and allows flow through the radiator to shed heat and prevent overheating.

There’s no strict service interval just for the thermostat, but it’s smart maintenance to inspect or replace it when doing bigger cooling system jobs. Many owners choose to fit a new thermostat proactively at high mileage or when replacing the timing belt and water pump on EJ engines, as the access overlaps and the part is relatively affordable.

• Common signs it’s on the way out: slow warm‑up, fluctuating temp gauge, overheating under load, weak cabin heat, radiator hoses staying cold too long, or a fault like P0128 (coolant temp below regulating threshold).
• Best practice on parts: use a genuine Subaru or OEM‑spec thermostat and a fresh gasket/O‑ring. Subaru units often have a jiggle‑pin bleed—orient it to 12 o’clock during install.
• Coolant: stick with the Subaru‑specified long‑life (blue) coolant or approved equivalent, mixed correctly. Don’t mix different coolant chemistries or colours.

1. Drain enough coolant to sit below the housing level, remove the housing, swap the thermostat, and refit with a clean sealing surface.
2. Torque housing bolts to the spec in the workshop manual and refill with the correct mix.
3. Bleed air fully (heater on hot, engine at fast idle, cap off until bubbles stop), then check for leaks and top up the radiator and overflow bottle.

Look under the bonnet periodically for crusty deposits, seepage at the housing, and hose condition. Keeping the cooling system in top nick helps the Exiga handle Aussie and Kiwi summer heat without breaking a sweat.

• Where is the thermostat on a 2010 Subaru Exiga?
  It sits in the thermostat housing at the front of the engine, by the lower radiator hose and water pump. Access is usually from underneath with the splash guard off. Draining some coolant first avoids a big mess, and the housing comes off with a few bolts.
• What temperature does the Exiga thermostat open?
  Most EJ20 Exiga thermostats begin opening in the low‑80s °C range and are fully open a bit higher. Exact figures vary by part number and market, so checking the service manual or the markings on the new thermostat is the safest bet.
• Should it be replaced with the timing belt or water pump?
  Yes, that’s popular. On EJ engines, the water pump and thermostat live in the same area. If the timing belt and pump are off, adding a fresh thermostat and gasket is cheap insurance against future cooling headaches.