P0118 2018 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 2018 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.
Code P0118 2018 GMC Sierra Description
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.
What are the Possible Causes of the DTC P0118 2018 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 2018 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 2018 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 2018 GMC Sierra code?
Need more information on how to fix the P0118 2018 GMC Sierra code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P0118 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P0118 2018 GMC Sierra Code
1. What does OBDII code P0118 on a 2018 GMC Sierra mean?
The P0118 code indicates a high input signal from the Engine Coolant Temperature (ECT) sensor circuit.
2. What are the common symptoms of OBDII code P0118 in a 2018 GMC Sierra?
Common symptoms include engine overheating, rough idling, poor fuel economy, and the Check Engine light illuminating on the dashboard.
3. What can cause the OBDII code P0118 in a 2018 GMC Sierra?
Potential causes of the P0118 code include a faulty ECT sensor, a corroded or damaged connector/wiring, low coolant levels, or a malfunctioning thermostat.
4. How can I diagnose the OBDII code P0118 in my 2018 GMC Sierra?
Diagnosing the P0118 code involves checking the ECT sensor and its wiring for any visible damage, testing the sensor's resistance, and verifying coolant levels and system operation.
5. Can I continue driving my 2018 GMC Sierra with the P0118 code?
It is not recommended to continue driving with the P0118 code, as it can lead to potential engine damage from overheating or incorrect temperature readings.
6. How can I repair the OBDII code P0118 in my 2018 GMC Sierra?
Repairing the P0118 code may involve replacing the ECT sensor, repairing any damaged wiring or connectors, topping up coolant levels, or addressing any thermostat issues.
7. Will resetting the Check Engine light resolve the P0118 code in my 2018 GMC Sierra?
Resetting the Check Engine light may temporarily clear the code, but if the underlying issue causing the P0118 code is not addressed, the light will likely come back on.
8. Can a DIY enthusiast fix the OBDII code P0118 in a 2018 GMC Sierra?
Depending on your mechanical skills and access to tools, some DIY enthusiasts may be able to address the P0118 code by replacing the ECT sensor or checking for wiring issues.
9. How much does it cost to repair the OBDII code P0118 in a 2018 GMC Sierra?
The cost of repairing the P0118 code can vary depending on the specific issue, but it may range from $100 to $300 for parts and labor at a dealership or repair shop.
10. Will passing a vehicle emissions test be possible with the OBDII code P0118 in my 2018 GMC Sierra?
Having an unresolved P0118 code may cause your vehicle to fail an emissions test, as it signifies a problem with the engine's coolant temperature circuit.
Discuss the causes and fixes for P0118 2018 GMC Sierra OBDII Code
Code P0118 2018 GMC Sierra comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
