Error P0118 - Coolant temperature sensor - high signal level

Error code P0118

Error P0118 indicates a high coolant temperature sensor level.

What does error P0118 mean?

Error P0118 is a common error code indicating that the engine control module (ECM) has detected too high a voltage in the coolant temperature sensor circuit (greater than 4.91).

Causes of error P0118

If the output temperature of the coolant temperature sensor is more than 4.91 V, the vehicle ECM detects a fault in the sensor circuit and registers error code P0118.

Symptoms of error P0118

• If this error occurs, the Check Engine indicator on the vehicle's instrument panel lights up. The ECM will reset the engine to emergency mode and will replace the incorrect coolant temperature sensor reading with 80 ° C (176 ° F).
• The car's engine starts hard when cold. When warmed up, the engine starts normally.
•  
• The car's engine runs erratically until it warms up.
•  
• After warming up, the engine usually runs normally.

Note: The symptoms of this error may vary depending on the make and model of the car.

How to diagnose error P0118

To diagnose this error, follow these steps:

1. Visually inspect the coolant temperature sensor, as well as the relevant electrical wires and connector.

2 Calculate all saved data and error codes using the OBD-II scanner to find out when and under what circumstances error P0118 occurred.

3. Clear the error codes from the computer's memory and run a car test drive to see if the P0118 code reappears.

4. Check the electrical wires and the coolant temperature sensor connector for corrosion and damage.

5. To check up indications of the gauge of temperature of cooling liquid in real time, using the scanner.

6. If necessary, replace the coolant temperature sensor, the appropriate electrical wires and the connector or engine control module (ECM).

Frequent errors when diagnosing code P0118

- Neglect visual inspection of the coolant temperature sensor, as well as the corresponding electrical wires and connector.
- Failure to comply with the diagnosis protocol.
- Hasty replacement of the coolant temperature sensor.
- Neglect to check the new coolant temperature sensor before final installation. After connecting the sensor, it is necessary to check what temperature value the sensor transmits to the ECM of the car

Is error P0118 serious?

If error P0118 occurs, the vehicle ECM sets the engine to emergency mode. Being in emergency mode can cause the engine to run erratically, which will continue until the engine warms up to normal operating temperature. It is possible to increase fuel consumption and the accumulation of excess carbon on engine components. Driving in an emergency mode for a long time can lead to other problems, including problems with the ignition system. Also, the cooling system fans can run continuously.

Repair to fix P0118

• Repair or replace the electrical connector of the coolant temperature sensor.
• Repair or replacement of electrical wires related to the coolant temperature sensor.
• Coolant temperature sensor replacement.

You can read more in this article.

Additionally:

The most common cause of error P0118 is a break in the coolant temperature sensor circuit.