What does the Atag Error 80 fault code mean?

Your boiler has shut down because the exhaust gases have become too hot, which is a safety measure to prevent damage to the internal components.

How much does it cost to fix Atag error code Error 80?

Typical repair cost for the Atag Error 80 fault is £150-350 including labour.

maximum flue gas sensor temperature exceeded

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Each noise points to a different fault.

Sludge build-up — needs flushing, not bleeding.

Safety-critical — turn off, read this.