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P0118 Saturn Code - Engine Coolant Temperature Circuit High Input

Quick Answer

The P0118 diagnostic trouble code (DTC) for Saturn vehicles indicates an issue with the Engine Coolant Temperature (ECT) sensor circuit registering a high input. Common causes include Faulty ECT Sensor: The ECT sensor itself may be malfunctioning, providing incorrect high voltage readings to the ECM, Wiring Issues: Damage or corrosion in the wiring connecting the ECT sensor to the ECM can cause a high input signal, ECM Malfunction: A problem with the engine control module can also trigger the P0118 code by misinterpreting the ECT sensor data. 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 Saturn indicates Engine Coolant Temperature Circuit High Input.
Common causes
Common causes include Faulty ECT Sensor: The ECT sensor itself may be malfunctioning, providing incorrect high voltage readings to the ECM, Wiring Issues: Damage or corrosion in the wiring connecting the ECT sensor to the ECM can cause a high input signal, ECM Malfunction: A problem with the engine control module can also trigger the P0118 code by misinterpreting the ECT sensor data.
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 Sep 12, 2024
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Code P0118 Saturn Description

The P0118 diagnostic trouble code (DTC) for Saturn vehicles indicates an issue with the Engine Coolant Temperature (ECT) sensor circuit registering a high input. The ECT sensor is responsible for monitoring the temperature of the engine coolant and sending this information to the engine control module (ECM). When the ECM detects a high voltage signal from the ECT sensor that is outside of the normal operating range, it triggers the P0118 code.

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

Common Causes of P0118 Saturn

  1. Faulty ECT Sensor: The ECT sensor itself may be malfunctioning, providing incorrect high voltage readings to the ECM.
  2. Wiring Issues: Damage or corrosion in the wiring connecting the ECT sensor to the ECM can cause a high input signal.
  3. ECM Malfunction: A problem with the engine control module can also trigger the P0118 code by misinterpreting the ECT sensor data.
  4. Coolant System Problems: Issues with the coolant system, such as low coolant levels or a malfunctioning thermostat, can also lead to incorrect temperature readings.

Symptoms of P0118 Saturn

  1. Check Engine Light: The most common symptom associated with the P0118 code is the illumination of the Check Engine Light on the vehicle's dashboard.
  2. Engine Overheating: A faulty ECT sensor providing a high input signal may cause the engine to overheat due to incorrect temperature readings.
  3. Poor Fuel Efficiency: Incorrect engine temperature readings can lead to poor fuel efficiency as the ECM may not be able to adjust the fuel mixture accurately.
  4. Rough Idling: The engine may experience rough idling or stalling due to incorrect temperature data affecting engine performance.

How to Fix P0118 Saturn

  1. Diagnose the Issue: Use a scan tool to read the code and check the ECT sensor's voltage readings to determine if the sensor is providing a high input signal.
  2. Replace ECT Sensor: If the ECT sensor is faulty, replace it with a new sensor following the manufacturer's guidelines.
  3. Check Wiring: Inspect the wiring connecting the ECT sensor to the ECM for any damage or corrosion, repairing or replacing as needed.
  4. Test ECM: If all other components check out, test the ECM to ensure it is functioning correctly and replace if necessary.
  5. Clear Codes: After completing the repair, clear the DTC and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0118 Saturn

The typical repair costs for addressing a P0118 code on a Saturn vehicle can range from $100 to $300, depending on the specific cause of the issue and the cost of parts and labor in your area. It's important to note that diagnosis time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate. Keep in mind that rates at dealerships or in metropolitan areas may be higher, while independent shops often offer more competitive pricing.

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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.

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