How do you diagnose error code 118 high temperature input Audi a4?

Diagnostic error code number 118 with high temperature input on a Audi A4 means that the engine coolant is not running at the right temperature. When the engine is cold, it should be warm, and when the engine is warm, the temperature should be cooler in the engine. The problem could be with the Engine Coolant Temperature sensor or the vehicle could be low on fluid.