What does the Ariston A18 fault code mean?

Your boiler has detected that water is not moving around the system properly, which has caused it to shut down to prevent overheating.

How much does it cost to fix Ariston error code A18?

Typical repair cost for the Ariston A18 fault is £180-£350 including labour.

Check the pressure gauge and top up to 1.5 bar if it is too low

No water circulation

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.

Lockout fault with a reset-needed pattern.