DTC P2181-00: Cooling System Performance: General Description

A thermostat is a component of an HVAC control system which is installed in the coolant passage between engine and radiator and it is block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the engine. Once the engine reaches it operating temperature, the thermostat opens. By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions.