Thermocouple going out on furnace

[Plumber69]

Thermocouple is going out on furnace once or twice a day, I noticed the pilot assembly was covered in black soot. There was a small leak in the pilot tube connecting to the assembly. Fixed leak, could of this been shorting out the thermocouple if the leak caught flame

 

[WorthFlorida]

Probably caused a wrong air fuel mixture with a leak and the flame was not hot enough to keep the pilot thermocouple active.