AutoCodes – GMC – P0118 2016 GMC Sierra

P0118 2016 GMC Sierra Code - Engine Coolant Temperature Circuit High Input

Quick Answer

The Engine Coolant Temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. Common causes include Low engine coolant level, Leaking or stuck open 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: P0118 2016 GMC Sierra indicates Engine Coolant Temperature Circuit High Input.
Common causes: Common causes include Low engine coolant level, Leaking or stuck open 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 278

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 May 20, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0118 2016 GMC Sierra Description

The Engine Coolant Temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The Engine Control Module (ECM) supplies 5 V to the ECT sensor signal circuit and a ground for the low reference circuit.
The ECM uses this high side coolant rationality diagnostic to determine if the input from the ECT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the ignition is OFF. If the calibrated ignition OFF time is met at start-up, the ECM will compare the temperature difference between the ECT and the intake air temperature (IAT) to determine if the temperatures are within an acceptable operating range of each other. The Diagnostic Trouble Code (DTC) will be set when the ECM detects a the ECT is colder than -39°C (-38°F) for greater than 5 s.

OBDII Code P0118 2016 GMC Sierra - Engine Coolant Temperature Circuit High Input - AutoCodes.com — P0118 2016 GMC Sierra Code - Engine Coolant Temperature Circuit High Input

What does this mean?

What are the Possible Causes of the DTC P0118 2016 GMC Sierra?

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

How to Fix the DTC P0118 2016 GMC Sierra?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0118 2016 GMC Sierra 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.

Need more information about the P0118 2016 GMC Sierra code?

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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.