P0118 Code: Meaning, Causes, Symptoms, (& How to Fix it)

Coolant is one of the most important fluids used in the latest vehicles. It is used to cool the engine. It plays a big role in preventing the engine from overheating. The vehicle contains different sensors to monitor the functionality of different engine parts. The vehicle contains an engine coolant temperate (ECT) sensor that monitors the temperature of the coolant. The powertrain control module (PCM) of the vehicle utilizes the data of the ECT sensor to control the supply of coolant to the engine. When your PCM notices an issue with the ECT sensor, it triggers the P0118 code. This article mainly explains the P0118 code causes, symptoms, and how to fix it.

P0118 Code Definition

P0118 code stands for “Engine Coolant Temperature Circuit High Input.”

What does the P0118 Code mean?

The P0118 code indicates that your powertrain control module (PCM) observes a high voltage input (normally over 4.7V) from the coolant temperature circuit.

P0118 code

The main function of the engine coolant temperature (ECT) sensor is to monitor a variation in the temperature of the engine coolant. After collecting the coolant temperature information, the ECT sensor transfers this information to your ECM/PCM.

The ECM/PCM utilizes the data of the ECT sensor to control the ignition spark timing, cooling fans, and air-fuel ratio required to your engine. 

Symptoms of Code P0118

  • Illuminated check engine light
  • Poor engine performance
  • Rough idling
  • Difficult to start the car
  • Higher fuel consumption than usual

Causes of Code P0118

  • Insufficient engine coolant
  • Dirty coolant
  • Damaged engine coolant temperature sensor
  • Damaged or frayed wires to the engine coolant temperature sensor
  • Bad PCM
  • Open engine coolant temperature sensor circuit

How to diagnose the P0118 Code?

  • Ensure the existence of the P0118 code by using a scan tool.
  • Collet the freeze data to find the main issue.
  • Clear the codes and reset the system to check if the code returns.
  • Inspect the electrical wires connected to the engine coolant temperature sensor.
  • Inspect the connectors to the engine coolant temperature sensor.
  • Check the coolant level in the engine.
  • Check the coolant condition. Your coolant must be contaminated-free.
  • Inspect the engine coolant temperature sensor for damage.

Common Diagnostic Mistakes of P0118 Code

  • Replacing the ECT sensor without checking the coolant level.
  • Not visually inspecting the problem area first.
  • Not inspecting the coolant condition.
  • Replacing the engine coolant temperature sensor without inspecting the damaged wiring.

Fixing Costs for P0118 Code

To fix the P0118 code, you can expect a variety of costs involved. Following are a few parts that you may need to repair or replace to fix the P0118 code:

PartsCost
Engine coolant temperature sensor replacement$130 to $220
Wiring repair/replacement$90 to $1100
Coolant Flush$90 to $160
PCM replacement$945 to $1,040

FAQ Section

How serious is the P0118 Code?

The P0118 code is a serious trouble code. This trouble code may produce different drivability issues, such as turning the vehicle into limp mode. The limp mode leads to rough idling and acceleration issues. The limp mode may also lead to poor fuel economy and carbon fouling of engine components. You shouldn’t drive your vehicle with the P0118 code for an extended period of time. Driving with this code for a long time may lead to the complete failure of the engine.

What repairs can fix the P0118 Code?

  • Fixing the loose ECT sensor connectors
  • Adding more coolant if needed
  • Changing the coolant if needed
  • Replacing the engine coolant temperature sensor 
  • Fixing the issues related to the powertrain control module (PCM)
  • Fixing the open engine coolant temperature sensor circuit

How to fix Code P0118?

You need to repair one or more of the following parts to fix the P0118 code:

  • Adding more coolant if needed
  • Changing the coolant if needed
  • Fixing the open engine coolant temperature sensor circuit
  • Replacing the engine coolant temperature sensor 
  • Fixing the loose ECT sensor connectors
  • Fixing the issues related to the powertrain control module (PCM)

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