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Home >> Lexus >> 2025 >> NX 350h >> Repair and Diagnosis >> External Pages >> Different car >> Section 101 (Engine Control System - Diagnostic Codes (P0087-P012F)) >> SFI System >> DTC P0115-15: Engine Coolant Temperature Sensor 1 Circuit Short to Battery or Open [11/2021 - ] >> Monitor Description

Monitor Description

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

Example:

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