What does the Atag 78 fault code mean?

Your boiler has detected that the water pressure inside your heating system is either too low or too high, so it has safely shut down to prevent damage.

How much does it cost to fix Atag error code 78?

Typical repair cost for the Atag 78 fault is £80-150 including labour.

Can I fix Atag fault code 78 myself?

Locate the external filling loop, which is usually a small silver braided hose with one or two valves underneath the boiler.

Atag 78 Fault Code: What It Means & How to Fix It

Technical description

Water pressure outside of range or not connected

Engineer required

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

Find a Gas Safe engineer

Search the official register →

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Your boiler has detected that the water pressure inside your heating system is either too low or too high, so it has safely shut down to prevent damage.

Technical description

Engineer required

Related guides you might find useful

Boiler keeps losing pressure

Low pressure — repressurise guide

When to replace your boiler

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