Your boiler has detected that the fuel type it is being supplied with does not match its internal settings, causing it to shut down for safety.

Incorrect gas type (referenced in status code S.61)

What causes this fault?

This fault occurs when the boiler's internal sensors detect that the gas being burned does not match the settings programmed into the control board. The most common reason is a communication error or mechanical failure within the gas valve or the venturi assembly, which prevents the boiler from regulating the fuel mix correctly. In some cases, it can be triggered after a new installation if the engineer has not correctly configured the boiler for the specific type of gas in your area.