If you own a vehicle and are experiencing issues with the engine coolant
temperature circuit, you may see the P0116 code appear on your dashboard. This
code indicates a range or performance problem in the engine coolant temperature
circuit, and it's important to diagnose and address the issue promptly to avoid
further damage to your vehicle. In this guide, we will explain the meaning of
the P0116 code and provide a step-by-step guide to help you troubleshoot the
What does the P0116 code mean?
The P0116 code is a diagnostic trouble code (DTC) that indicates a range or
performance problem in the engine coolant temperature (ECT) circuit. This code
is typically triggered when the engine control module (ECM) receives a signal
from the ECT sensor that is outside of the normal range. The ECT sensor is
responsible for measuring the temperature of the engine coolant and sending this
information to the ECM, which uses it to adjust the fuel mixture and ignition
timing. If the ECT sensor is malfunctioning, it can cause a variety of problems
with the engine, including poor performance, decreased fuel efficiency, and even
Step-by-Step Guide to Troubleshooting the P0116 Code
Step 1: Check for other codes
Before you start troubleshooting the P0116 code, it's a good idea to check for
other codes that may be related to the engine coolant temperature circuit. If
you see any additional codes, address those issues first before proceeding with
the P0116 code.
Step 2: Inspect the ECT sensor
The first step in troubleshooting the P0116 code is to inspect the ECT sensor.
The sensor is typically located on the engine block or in the thermostat
housing, and it's connected to the engine wiring harness. Check the wiring and
connections for any signs of damage, wear, or corrosion. If everything looks
okay, test the resistance of the ECT sensor using a multimeter. Compare the
readings with the manufacturer's specifications. If the readings are outside of
the acceptable range, the sensor needs to be replaced.
Step 3: Check the thermostat
The thermostat is responsible for regulating the flow of coolant through the
engine. If the thermostat is stuck open or closed, it can cause the engine to
overheat or run too cool, which can trigger the P0116 code. To check the
thermostat, start the engine and let it idle until it reaches normal operating
temperature. Then, use a temperature gun or thermometer to measure the
temperature of the upper radiator hose. If the temperature is significantly
cooler than the engine temperature, the thermostat may be stuck open and needs
to be replaced.
Step 4: Inspect the coolant system
The engine coolant system is a closed system that circulates coolant through the
engine to regulate its temperature. If there is a leak in the system, it can
cause the engine to overheat or run too cool, which can trigger the P0116 code.
Inspect the coolant system for any signs of leaks, such as coolant stains or a
drop in the coolant level. If you find a leak, repair it and refill the system
with the recommended coolant.
Step 5: Check the ECM
If all of the previous steps have not resolved the issue, it's possible that the
problem lies with the ECM itself. A malfunctioning ECM can cause a variety of
problems with the engine, including issues with the engine coolant temperature
circuit. To check the ECM, you will need to use a diagnostic tool that is
compatible with your vehicle's make and model. If the tool indicates that the
ECM is malfunctioning, it will need to be replaced.
The P0116 code is a serious issue that can cause a variety of problems with the
engine, including decreased performance and decreased fuel efficiency. However,
by following this step-by-step guide, you can troubleshoot and diagnose the
issue with your engine coolant temperature circuit. Always remember to follow
the manufacturer's recommendations when working on your vehicle. Addressing the
P0116 code promptly will help you avoid further damage to your vehicle and keep
it running smoothly for years to come.