System Description/Monitoring Procedure
WARNING: This page is about a different car, the 2010 Suzuki Kizashi. However, it is still accessible from the selected car via links, so may be relevant.
The engine coolant temperature is estimated to model accumulated combustion heat value from engine start (based on mass intake air flow) and radiation heat value (radiation from engine, radiation when fuel shut-off, etc.). Malfunction is detected when estimated temperature reaches the specified temperature and the measured temperature is lower than criteria.