Vaillant · Turbomax Plus Boilers
This indicates a problem during the initial phase of the EcoTEC Pro / EcoTEC Plus boiler's fan starting up when operating in heating mode.
Click steps to track your progress.
Turn off the boiler at the main electrical supply for a few minutes, then restart it.
Check for any physical obstructions around the boiler's air intake and flue.
If the error reoccurs, contact a qualified heating engineer to inspect or replace the fan unit.