ATAG · iC, iS and iR range

612Fan failed to start

This code applies to iC Economiser, iC Combination, iS System, iR Regular. Fault codes narrow down the likely problem, but they do not replace a model-specific diagnosis.

What you can safely check

Do not open the case or inspect the fan or flue yourself.
Arrange a Gas Safe registered engineer.

How an engineer may fix it

Check fan movement and speed feedback, wiring and connectors, air/flue restrictions and the control board; repair or replace the defective part and verify combustion.

Manufacturer source: ATAG — Boiler Troubleshooting (2019 & newer i-range). Checked 15 August 2026. The appliance manual and an engineer’s on-site diagnosis take precedence. Never remove the boiler case yourself.