Monitor Description

WARNING: This page is about a different car, the 2020 Toyota RAV4 and 2019 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.

The engine coolant temperature sensor is used to monitor the engine coolant temperature. The engine coolant temperature sensor has a thermistor with a resistance that varies according to the temperature of the engine coolant. When the engine coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance decreases. These variations in resistance are reflected in the output voltage from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the engine coolant temperature. If the engine coolant temperature sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the engine coolant temperature sensor circuit, illuminates the MIL and stores a DTC.

Example:

If the engine coolant temperature sensor output voltage is higher than 4.91 V for 0.5 seconds or more, the ECM will illuminate the MIL and store this DTC.