Parts for your 2015 Subaru Exiga-Thermostat

2015 Subaru Exiga thermostat — purpose, servicing and replacement

Based on Subaru’s factory service information (Exiga/Crossover 7 YA/YAM series Cooling System section), the Subaru Global Technical Information System (STIS) and dealer parts catalogues for 2015 Exiga variants (FB25 and EJ20 engines), the vehicle is fitted with a wax‑pellet engine coolant thermostat. It sits in the lower hose/water pump housing and is absolutely relevant to engine warm‑up and temperature control.

The thermostat’s job is simple but critical: help the engine reach operating temperature quickly, then hold it steady. When cold, it stays shut so coolant circulates within the block for a faster warm‑up, better fuel economy and a toasty heater. Once it’s at temp, it opens to let coolant flow through the radiator and shed heat. If it sticks shut, the Exiga can overheat, if it sticks open, it runs too cool, drinks more fuel and the heater goes lukewarm.

Subaru doesn’t set a fixed replacement interval for the thermostat, it’s typically replaced on condition, or proactively during major cooling system work. A sensible approach on a 2015 Exiga is to assess it at coolant change time (around 10 years/200,000 km for Subaru Super Coolant, or earlier if history’s unclear). Always renew the thermostat gasket/O‑ring and use an OE‑quality thermostat matched to your engine code.

• Common signs it’s due: temp gauge creeping or bouncing about, slow warm‑up, poor cabin heat, radiator fans cycling oddly, overheating under load, or rusty/sludgy coolant.

DIY or workshop, a tidy replacement process looks like this: start stone cold, drain enough coolant to drop the level below the housing, remove the lower hose/housing, swap the thermostat and seal, clean mating faces, and torque fasteners to the workshop spec. Refill with the correct Subaru blue long‑life coolant (pre‑mix), bleed air with the heater on HOT, and run until both radiator fans cycle. Under the bonnet, check for leaks, confirm heater performance and steady gauge behaviour on a decent road test. While you’re there, inspect hoses, clamps and the radiator cap. A fresh cap and clean coolant go a long way towards keeping an Exiga happy across Aussie and Kiwi climates.

Popular questions

Where is the thermostat on a 2015 Subaru Exiga?
It’s mounted at the engine end of the lower radiator hose, in the water pump housing. Access is from underneath or through the front, and a drain tray helps keep things neat.

What coolant should be used after changing the thermostat?
Use Subaru Super Coolant (blue) or an approved equivalent that meets the same spec, pre‑mixed 50/50. Mixing types or using tap water can shorten component life.

Is it safe to drive with a dodgy thermostat?
Not recommended. A stuck‑shut stat risks overheating and engine damage, stuck‑open causes poor economy and rough running. Sort it before a long trip, especially in hot weather or alpine conditions.