2026-10-08 · 5 min read
Subaru WRX Thermostat Replacement Malaysia
A faulty thermostat on the WRX causes either overheating if it sticks closed, or sub-optimal engine temperature if it sticks open — both conditions are harmful to the FA20DIT turbo engine. An engine running below operating temperature increases fuel consumption and cylinder wall wear; overheating risks head gasket damage. Replace the thermostat as a precaution during major cooling system work or if temperature gauge readings become erratic. Use a genuine Subaru thermostat to ensure correct opening temperature calibration for the FA20DIT.
Subaru WRX Thermostat
- WRX FA20DIT thermostat: opens at approximately 82°C; slightly lower than FB25 to help manage turbo heat; thermostat housing is integrated with the water outlet — replace housing and thermostat together
- WRX thermostat stuck open: engine temp stays low on cold days; AFR runs rich for extended cold enrichment; boosts may be limited by ECU cold protection; replace thermostat; do not run WRX with open thermostat long-term
- WRX sport thermostat: some WRX owners fit lower-temperature thermostats (76°C) to keep engine cooler under boost; this is a track mod — on street, too-low thermostat causes oil contamination and fuel economy loss in Malaysia cool mornings
- WRX coolant and thermostat: if WRX runs hot (above 3/4 gauge) — check thermostat stuck closed; also check water pump and coolant level; FA20DIT overheating is serious — pull over immediately and investigate; do not continue driving