2026-10-08 · 5 min read
Subaru Outback Thermostat Replacement Malaysia
The thermostat on the Subaru Outback controls when coolant circulates through the radiator. A stuck-open thermostat causes the engine to run cool, reducing efficiency and increasing fuel consumption. A stuck-closed thermostat is more dangerous, causing rapid overheating in Malaysia's climate. Given the boxer engine's sensitivity to overheating, replacing the thermostat as a precautionary measure during a coolant flush is good practice on higher-mileage units. Always replace with a genuine or quality OEM thermostat to ensure correct opening temperature.
Subaru Outback Thermostat
- Outback FB25 thermostat: 88°C opening; same family as Forester thermostat; inspect housing at 100,000 km; EZ36 H6 uses different thermostat — EZ36 runs slightly different thermal map than FB25
- Outback EZ36 thermostat: H6 has two thermostats (one per bank) due to boxer H6 configuration; if one thermostat fails, only half the cooling circuit is affected — uneven temperature between banks; SSM4 live data shows coolant temp per bank
- Outback heater failure: if Outback heater blows cold air only — thermostat stuck open is leading cause (engine never reaches operating temperature); also check coolant level first (low coolant also causes poor heater output)