Monitor Description
WARNING: This page is about a different car, the 2016 Toyota Highlander, 2015 Toyota Highlander, and 2014 Toyota Highlander. However, it is still accessible from the selected car via links, so may be relevant.
The ECM monitors the difference between the engine coolant temperature and the intake air temperature when the engine is started cold to accurately detect the engine temperature conditions. The monitor runs when the engine is started after 7 hours or more have elapsed since the engine was stopped (power switch turned off) on the previous trip. If the difference between the engine coolant temperature and the intake air temperature on a cold start exceeds 25°C (45°F), the ECM interprets this as a malfunction in the engine coolant temperature sensor circuit and intake air temperature sensor circuit, and stores this DTC.