In the picture below, we show a customer who had a dirty PID probe that can affect the measurement of the temperature of the water in the coffee boiler. This same issue can occur with the steam boiler. In both boilers, this PID sensor, coated with calcium or other water minerals, will allow the machine to overheat that the programmed temperature.
It is imperative to use softened water to avoid this issue which can happen on any espresso machine with a PID sensor. The PID sensor can be cleaned with a wire brush. However, if too much damage was done, it may need replacement.

