Hello. I have a vallient ecomax 828 which is displaying the F40 fault code after a power cut earlier today. The boiler sounds like its running, but nothing is happening.

SOURCE: the code E 13 comes up on the panel and it cuts out

Maximum temp exceeded on ntc1(thermistor),,,either clean out heat exchanger,power flush of my first option replace thermistor...

SOURCE: Vailiant Ecomax 828 2e

Check the pressure relief valve & the pipe to the outside

SOURCE: Vaillant ecoMAX 828/2boiler goes on & off when running hot water!

water must be set at 3lts a min ,check diaphragm valve move when hot tap is on, check microswitch ,best of luck

SOURCE: Vaillant boiler no heating or hot water

pressure is down