For clarity, it’s the pitot tube heater that may fail. The pitot tube itself is a static instrument with nothing more than a pressure transducer that measures the difference between the static and dynamic pressure. This difference is used to calculate relative velocity (which is why F1 cars use pitot tubes to calculate the car’s speed).

Because the pitot tube sticks out in the airstream it’s subject to icing, similar to the leading edges of wings, which is why an internal heater is used. I know on many smaller airplanes the pilot must manually engage the heater when icing may occur. I don’t know if this is an automated function on large commercial airplanes though.

Sorry, a bit OCD, I know .