[Missile Man]

I found this, hope it helps.

Trouble Code: P0116
ECT Sensor / CHT Sensor Signal Range/Performance

Possible Causes:
Check for low coolant level or incorrect coolant mixture
CHT sensor is out-of-calibration or it has failed
ECT sensor is out-of-calibration or it has failed

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P0116 - OBD-II Trouble Code
Auto Systems and Repair
Engine Coolant Temperature Circuit Range/Performance Problem

Our emissions expert has put together the following information about the P0116 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.

OBD II Fault Code

OBD II P0116
Fault Code Definition

Engine Coolant Temperature Circuit Range/Performance Problem
What does Mean?
The Engine Coolant Temperature Sensor measures the rise and fall of the Engine Coolant Temperature. This provides critical data needed for the Powertrain Control Module (PCM) to control the Air Fuel Ratio, the Ignition Spark Timing, the cooling fans, and many components of the Emissions Control Systems. The Engine Coolant Temperature Sensor converts the coolant temperature into a voltage that is high when the engine is cold and low as the engine warms up.

Code P0116 is set when the Powertrain Control module sees irrational out of specification voltage signals from the coolant temperature circuit.

Symptoms

Check Engine Light will illuminate
In many cases, no abnormal symptoms may be noticed
In some cases, the engine may be hard starting and/or get poor fuel economy
Common Problems That Trigger the P0116 Code

Defective Engine Coolant Temperature Sensor
Rusty and/or corroded Engine Coolant
Faulty or corroded Engine Coolant Temperature wiring or connections

Common Misdiagnoses
Engine Coolant Temperature Sensor is replaced when the real cause is rusty coolant
Engine Coolant Temperature Sensor is replaced when the real cause is a poor connection or chafed wiring
Engine Coolant Temperature Sensor is replaced when the real problem is in the Cooling System
Polluting Gases Expelled

HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas
NOX (Oxides of Nitrogen): One of the two ingredients that, when exposed to sunlight, cause smog
P0116 Diagnostic Theory for Shops and Technicians
When diagnosing a P0116 code, it is important to record the freeze frame information and then to duplicate the code setting conditions with a test drive while paying close attention to engine load, throttle position, RPM, and road speed on a data streaming scan tool. As you drive the vehicle, compare these values to the Coolant Temperature Sensor PID or parameter ID. The Coolant Temperature Sensor voltage values should rise and fall with changes in engine temperature. Compare the Engine Coolant Temperature or ECT readings to the Intake Air Temperature Sensor readings, as they should move in tandem with each other. However, the Engine Coolant Temperature sensor will have a much higher temperature range.

Check the ECT sensor connector with the key on and the engine off. There needs to be a steady 5 volt reference voltage and a very good ground. Find and use the proper engine performance wiring diagram to discern the proper color and position of these wires in the connector.

It never hurts to do a key on-engine off voltage output test of the ECT sensor. Typically, I CAREFULLY use a heat gun to raise the temperature of the area around the sensor and study the change in values of the Coolant Temperature Sensor circuit. It's important to use the scan tool data stream as this will verify the ECT harness and connections.