System Description / Monitoring Procedure
WARNING: This page is about a different car, the 2008 Suzuki Grand Vitara. However, it is still accessible from the selected car via links, so may be relevant.
ECM monitors ECT sensor to ensure that temperature has dropped to environmental temperature. After 5 hours (using timer module) from engine stop, the system wakes up ECM and measures ECT and IAT signal. If difference between ECT and IAT is more than the criteria, ECM will set DTC.