What does the Chaffoteaux 9.ii fault code mean?

Your boiler is overheating because water isn't flowing through it properly, so it has safely shut itself down to prevent damage.

How much does it cost to fix Chaffoteaux error code 9.ii?

Typical repair cost for the Chaffoteaux 9.ii fault is £150-350 including labour.

Excessive temperature rise across boiler - Low water flow rate (Pump defective/High resistance)

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.

Lockout fault with a reset-needed pattern.

Sludge build-up — needs flushing, not bleeding.