Monitor Description

WARNING: This page is about a different car, the 2025 Toyota Highlander, 2024 Toyota Highlander, and 2023 Toyota Highlander. However, it is still accessible from the selected car via links, so may be relevant.

The engine coolant temperature sensor (for water inlet housing side) is used to monitor the inlet side engine coolant temperature. The engine coolant temperature sensor (for water inlet housing side) 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 (for water inlet housing side) output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the engine coolant temperature sensor (for water inlet housing side) circuit, illuminates the MIL and stores a DTC.

Example:

If the engine coolant temperature sensor (for water inlet housing side) output voltage is higher than 4.91 V for 3 seconds or more, the ECM will illuminate the MIL and store this DTC.