The P0118 code is an OBD-II diagnostic trouble code that indicates a problem with the Engine Coolant Temperature Sensor (ECT) circuit, specifically a high input voltage reading. This sensor plays a crucial role in monitoring the temperature of the engine coolant, which is essential for the engine management system to function efficiently.
What Does the P0118 Code Mean?
OBD-II Code P0118 is defined as “Engine Coolant Temperature Circuit High Input.” This means that the Engine Control Module (PCM) has detected a voltage reading from the ECT sensor that exceeds the expected range, indicating a potential malfunction.
What Causes the P0118 Code?
The P0118 code can be triggered by a variety of issues, including:
- A defective Engine Coolant Temperature Sensor
- Rusty or corroded engine coolant
- Faulty or corroded wiring or connections related to the ECT sensor
- Issues within the cooling system that affect sensor readings
What Are the Symptoms of the P0118 Code?
Common symptoms associated with the P0118 code include:
- Illumination of the Check Engine Light
- In some cases, no noticeable symptoms may be present
- Potential hard starting of the engine
- Poor fuel economy
How Serious Is the P0118 Code?
The P0118 code is considered urgent, as it indicates a significant malfunction that can lead to severe damage to the vehicle or pose safety risks to the driver and passengers. It is crucial to address this code promptly to prevent potential engine overheating and other related issues.
How to Diagnose the P0118 Code
When diagnosing the P0118 code, follow these steps:
- Record freeze frame data and attempt to replicate the conditions that triggered the code.
- Use a scan tool to monitor the ECT sensor data stream during a test drive, observing engine load, throttle position, RPM, and road speed.
- Compare ECT readings with Intake Air Temperature Sensor readings, as they should correlate with each other.
- Check the ECT sensor connector for a steady 5-volt reference voltage and a good ground connection.
- Perform a voltage output test on the ECT sensor while carefully applying heat to the sensor area to observe changes in values.
Common Repairs for the P0118 Code
Typical repairs for the P0118 code may involve:
- Replacing the faulty Engine Coolant Temperature Sensor
- Flushing and replacing rusty or contaminated engine coolant
- Repairing or replacing corroded wiring and connectors associated with the ECT sensor
- Addressing any underlying cooling system issues
How Much Does It Cost to Fix the P0118 Code?
The cost to fix the P0118 code can vary widely based on the underlying issue:
- Replacing the ECT sensor may cost between $100 to $300, including parts and labor.
- Flushing the cooling system can range from $50 to $150.
- Wiring repairs can vary depending on the extent of the damage, potentially costing between $100 to $500.
Can I Fix the P0118 Code Myself?
While some DIY enthusiasts may be able to address minor issues, such as replacing the ECT sensor or flushing the coolant, diagnosing electrical problems or sensor issues may require specialized tools and knowledge. If you are not confident in your mechanical skills, it is recommended to seek professional assistance to ensure accurate diagnosis and repair.
