What does the Ariston 12 fault code mean?

Your boiler is struggling to keep your hot water at a steady temperature or at a strong enough flow rate.

How much does it cost to fix Ariston error code 12?

Typical repair cost for the Ariston 12 fault is £120-250 including labour.

Check of domestic hot water production efficiency (delivery rate and temperature)

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Almost always a stuck diverter valve on combis.

Each noise points to a different fault.

Sludge build-up — needs flushing, not bleeding.