SE code on the boiler?

Making the assumption that your boiler is a Worcester Bosch, the SE code is not a fault that requires resetting. SE means that the boiler is due for its service and comes on after a set time period. If for any other reason the boiler needs resetting, the reset button is pressed and held for a for a few seconds whilst the power is on, there is no need to disconnect the power.

Rupert
November 2019