AutoCodes – Lexus – P0115 Lexus

P0115 Lexus Code - Engine Coolant Temperature Circuit Malfunction

Quick Answer

The engine coolant temperature sensor is used to monitor the engine coolant temperature. Common causes include Low engine coolant level, Faulty Engine Coolant Thermostat, Faulty Engine Coolant Temperature (ECT) sensor. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0115 Lexus indicates Engine Coolant Temperature Circuit Malfunction.
Common causes: Common causes include Low engine coolant level, Faulty Engine Coolant Thermostat, Faulty Engine Coolant Temperature (ECT) sensor.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 21,097

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 23, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P0115 Lexus Description

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 coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are reflected in the output voltage from the sensor. The Engine Control Module (ECM) monitors the sensor voltage and uses this value to calculate the engine coolant temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the engine coolant temperature sensor circuit and stores a Diagnostic Trouble Code (DTC).

OBDII Code P0115 Lexus - Engine Coolant Temperature Circuit Malfunction - AutoCodes.com — P0115 Lexus Code - Engine Coolant Temperature Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0115 Lexus?

Low engine coolant level
Faulty Engine Coolant Thermostat
Faulty Engine Coolant Temperature (ECT) sensor
Engine Coolant Temperature sensor harness is open or shorted
Engine Coolant Temperature sensor circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0115 Lexus?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

Start by checking the engine coolant level at the coolant reservoir, a low level may indicate a coolant leak. If the coolant level is correct, you should replace the Engine Coolant Temperature (ECT) sensor to fix the problem. The Engine Coolant Thermostat must be replaced every time there is a repair with the coolant system.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0115 Lexus code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.