In maintaining your water heater it is always good to know what can contribute to water heater thermocouple problems.
Contamination or particle diffusion can alter your thermocouple's physical makeup and prevent it from conforming to required standards.
Poor Solder Joints
Loose solder joints may interfere with proper operation.
Stress or contamination on thin thermocouple wires may cause the thermocouple to alter temperatures they are designed to measure.
Output signals can be changed by noises because of the thermocouple's narrow gauge wiring.
Lack of oxygen may oxidize chromium used to make thermocouples. This oxidizing corrodes the thermocouple's wires.