Hello smjames69, thanks for your question in the community.
This fault Code means the following: P0116 - Engine Coolant Temperature (ECT) Sensor Performance
You can test the sensor by unplugging the coolant temperature Seonsor.
Another way is to check the values from the sensor in Engine Control Unit.
But in the most times its a faulty Sensor the Problem.
Check the cables and look for a Marten bite, maybe it could a Problem.