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The Engine Coolant Temperature (ECT) sensor is one of the many devices that relay information to your vehicle’s primary computer (Powertrain Control Module or PCM). The input from this sensor is used by the PCM for engine management and cooling fan operation. When the module detects erratic or irrational signals from this sensor, the P0116 code is set.
Here is a quick overview of what you need to know about the P0116 code.

What Does the P0116 Code Mean?

Diagnostic trouble code (DTC) P0116 stands for “Engine Coolant Temperature Sensor 1 Circuit Range/Performance.”

This DTC is triggered by the PCM after it detects that the voltage signals relayed by the engine coolant temperature (ECT) sensor fall outside the normal manufacturer-specified range.
The ECT sensor is a thermistor—a resistor that changes resistance based on temperature. This typically comes as a two-wire sensor that can be found in the block or cylinder head. One wire connects it to the PCM which supplies it with a 5 Volt supply, while the other is a ground.

cylinder head
The ECT sensor is a thermistor that can be found in the block or cylinder head.

A change in coolant temperature will cause a change in resistance on the ECT sensor’s signal wire. This data is used by the PCM to determine the current operating temperature of the engine. Inaccurate information from this sensor will cause the PCM to make adjustments according to false operating conditions, which could lead to reduced fuel economy and engine cooling system failure.

Note: The definition of code P0116 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

P0116 is a common issue among the following makes: Ford (especially a Ford Escape), Hyundai, Volkswagen, Mercedes Benz, and Toyota.

What are the Possible Causes of the P0116 Code?

  • Malfunctioning Engine Coolant Temperature Sensor
  • Faulty or corroded ECT wiring or connections
  • Engine overheating
  • Engine temperature below specification
  • An issue with the PCM, such as software in need of an update

What are the Common Symptoms of the P0116 Code?

  • Check Engine Light will illuminate
  • In many cases, this trouble code may not present unusual symptoms
  • In some cases, this code may reduce engine performance (hard starting and/or poor fuel economy)
  • Engine overheating
check engine light is on
An illuminated check engine light is one of the common symptoms of code P0016.

How to Diagnose the P0116 Code

Identifying the underlying cause of the P0116 code can be difficult, especially if you’re not confident with your automotive knowledge. In most cases, it would be best to bring your vehicle to an auto repair shop and seek the help of a professional for an accurate diagnosis.

Here are some videos that can help give you an idea about how this trouble code may be diagnosed:

How to Fix the P0116 Code

The P0116 code is a generic trouble code that may apply to various makes and models. While vehicles from different manufacturers may share common symptoms, the steps for diagnosis and repair for a P0116 Ford code may differ from a P0116 Hyundai code.

If you’re an advanced DIYer who’d like to fix this code on your own, it will be helpful to refer to repair manuals or get factory vehicle repair information from an online subscription service.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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