P0118 GMC 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 GMC 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 GMC 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 GMC?
- 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 GMC?
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 GMC 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 GMC code?
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Need Help with the Code?
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Information for Specific GMC Models
- P0118 2014 GMC Sierra — Engine Coolant Temperature Circuit High Input
- P0118 2015 GMC Sierra — Engine Coolant Temperature Circuit High Input
- P0118 2016 GMC Sierra — Engine Coolant Temperature Circuit High Input
- P0118 2017 GMC Sierra — Engine Coolant Temperature Circuit High Input
- P0118 2018 GMC Sierra — Engine Coolant Temperature Circuit High Input
Frequently Asked Questions about P0118 GMC Code
No Frequently Asked Questions about P0118 GMC Code found.
Discuss the causes and fixes for P0118 GMC OBDII Code
-
ive replaced the temp sensor. ive checked harness has 4.7. i replaced thermostat. and nothing!!! never been more frusterated!! its a 01 gmc sierra 2500. did a efan conversion and had it tuned at a shop he tells me its the sensor or a wire. ive checked everything!!!! what is wrong with this POS??
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Unfortunately, I haven't encountered that problem before. However, I checked a national database of repairs and found that the issue is usually caused by the sensor itself or its connector. A poor connection resulting from loose or rusted pins in the connector can set the code. You can try wiggling the connector while the engine is running a few times to see if that triggers the code.
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