Self-Check Engine

As SUBARU trouble code shows the error on water temperature sensor as #21, I determined to check error code by myself with the method of convention, just 1pin coupler connecting under the handle post.
Restored error would be reported by means of Morse signal on Check Engine lamp flashing. In case of the fault on the water temp one, I would lose the Legal Inspection definitely, because the mixture ratio should be fixed at richer value in case of water temperature dysfunction. Too much Carbon Oxide would be exhausted by the ECU control to pass the limited value below 4,5% inclusion.
So the Water Temp. sensor must be in healthy condition at any rate as indispensable component for a computer controlled engine.
Today and tomorrow the most busy mechanic I would be!