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P0118 Chevrolet Code - Engine Coolant Temperature Circuit High Input

Quick Answer

The P0118 code for Chevrolet vehicles indicates a problem with the Engine Coolant Temperature (ECT) sensor circuit, specifically that the input signal is reading higher than expected. Common causes include Faulty ECT Sensor: A malfunctioning ECT sensor can send incorrect temperature readings to the ECM, triggering the high input signal error code, Wiring Issues: Damaged or corroded wiring connections between the ECT sensor and the ECM can cause circuit high input problems, Coolant Level: Low coolant levels or air pockets in the cooling system can affect the ECT sensor's accuracy. 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 Chevrolet indicates Engine Coolant Temperature Circuit High Input.
Common causes
Common causes include Faulty ECT Sensor: A malfunctioning ECT sensor can send incorrect temperature readings to the ECM, triggering the high input signal error code, Wiring Issues: Damaged or corroded wiring connections between the ECT sensor and the ECM can cause circuit high input problems, Coolant Level: Low coolant levels or air pockets in the cooling system can affect the ECT sensor's accuracy.
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.
What is this?
Table of contents Created and updated by William Orellana on Aug 19, 2024
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Code P0118 Chevrolet Description

The P0118 code for Chevrolet vehicles indicates a problem with the Engine Coolant Temperature (ECT) sensor circuit, specifically that the input signal is reading higher than expected. The ECT sensor is responsible for measuring the temperature of the engine coolant and sending this information to the engine control module (ECM) to help regulate fuel mixture, ignition timing, and other engine functions. When the ECM receives a high input signal from the ECT sensor, it may cause the engine to run rich, resulting in decreased fuel efficiency, poor performance, and potential engine overheating.

OBDII Code P0118 Chevrolet - Engine Coolant Temperature Circuit High Input
P0118 Chevrolet Code - Engine Coolant Temperature Circuit High Input

Common Causes of P0118 Chevrolet

  1. Faulty ECT Sensor: A malfunctioning ECT sensor can send incorrect temperature readings to the ECM, triggering the high input signal error code.
  2. Wiring Issues: Damaged or corroded wiring connections between the ECT sensor and the ECM can cause circuit high input problems.
  3. Coolant Level: Low coolant levels or air pockets in the cooling system can affect the ECT sensor's accuracy.
  4. ECM Malfunction: In rare cases, a faulty ECM can cause erroneous readings from the ECT sensor, leading to the P0118 code.
  5. Overheating Issues: Engine overheating can also trigger this code if it affects the ECT sensor's ability to function properly.

Symptoms of P0118 Chevrolet

  1. Check Engine Light: The most common symptom associated with this code is the illumination of the check engine light on the dashboard.
  2. Engine Overheating: A malfunctioning ECT sensor can cause inaccurate temperature readings, leading to engine overheating.
  3. Poor Fuel Economy: The ECM may adjust the fuel mixture incorrectly due to the high input signal from the ECT sensor, resulting in decreased fuel efficiency.
  4. Rough Idle: The engine may experience rough idling or stalling due to improper fuel mixture adjustments.
  5. Reduced Performance: The vehicle may exhibit decreased performance, including sluggish acceleration and overall power.

How to Fix P0118 Chevrolet

  1. Diagnose the Issue: Use a diagnostic scanner to read the code and confirm the ECT sensor's high input signal.
  2. Inspect ECT Sensor: Check the ECT sensor for any signs of damage or corrosion and replace if necessary.
  3. Check Wiring: Inspect the wiring harness for any frayed wires, loose connections, or corrosion, and repair as needed.
  4. Verify Coolant Levels: Ensure that the coolant level is adequate and the cooling system is properly bled to prevent air pockets.
  5. Clear Codes and Test Drive: After making the necessary repairs, clear the fault codes from the ECM and test drive the vehicle to verify that the issue has been resolved.

Cost to Fix P0118 Chevrolet

The cost of repairing a P0118 code on a Chevrolet vehicle can vary depending on the specific cause of the issue. In general, replacing a faulty ECT sensor can cost between $50 and $150, while addressing wiring issues or coolant system problems may require additional labor and parts costs. The total repair bill, including parts and labor, can range from $100 to $300 or more. It's important to consult with a qualified mechanic or repair shop for an accurate estimate based on your vehicle's make and model, as well as local labor rates.

What does this mean?

Tech Notes for P0118 Chevrolet





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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.

Frequently Asked Questions about P0118 Chevrolet Code

1. What are the common symptoms of OBDII code P0118 (Chevrolet)?

The common symptoms of P0118 include the engine running hotter than normal, the temperature gauge reading unusually high, and potential issues with the vehicle's fuel efficiency.

2. What are the possible causes of OBDII code P0118 (Chevrolet)?

The potential causes of P0118 include a faulty engine coolant temperature (ECT) sensor, a malfunctioning thermostat, wiring issues in the ECT circuit, or low coolant levels.

3. How can I diagnose the OBDII code P0118 (Chevrolet)?

To diagnose P0118, you can use an OBDII scanner to retrieve the trouble code, visually inspect the ECT sensor and its wiring for any signs of damage, and test the sensor's resistance with a multimeter.

4. Can a faulty thermostat trigger OBDII code P0118 (Chevrolet)?

Yes, a faulty thermostat can cause the engine coolant temperature to be higher than normal, triggering the P0118 trouble code due to incorrect temperature readings being sent to the engine control module.

5. What are some repair tips for fixing OBDII code P0118 (Chevrolet)?

Repair tips for P0118 include replacing the ECT sensor if it is faulty, checking and replacing the thermostat if needed, ensuring proper coolant levels, and inspecting the wiring for any faults.

6. Is it safe to continue driving with OBDII code P0118 (Chevrolet) present?

It is not recommended to drive with P0118 as it can lead to engine overheating and potential damage. It's best to address the issue promptly to avoid more serious problems.

7. Can a low coolant level trigger OBDII code P0118 (Chevrolet)?

Yes, low coolant levels can impact the engine coolant temperature readings, causing the ECT sensor to detect high temperatures and trigger the P0118 trouble code.

8. How much does it typically cost to repair OBDII code P0118 (Chevrolet)?

The cost to repair P0118 can vary depending on the root cause of the issue. Generally, replacing the ECT sensor can cost between $50 to $200, while replacing a faulty thermostat can range from $100 to $300.

9. Will resetting the trouble code resolve OBDII code P0118 (Chevrolet)?

Resetting the trouble code may temporarily clear the check engine light, but if the underlying issue causing P0118 is not addressed, the code is likely to reappear.

10. Can a DIY enthusiast fix OBDII code P0118 (Chevrolet) at home?

Depending on the cause of P0118, DIY enthusiasts with automotive repair experience can potentially fix the issue at home by replacing the ECT sensor, checking the thermostat, and ensuring proper coolant levels. However, complex wiring issues may require professional assistance.

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