High Lockout
53:0 on Viessmann Vitodens 300-W

Your boiler has detected an internal electrical communication error or a fault with one of its main control components, which is preventing it from running properly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Function connection 28: Central fault

What causes this fault?

This fault occurs when the boiler's internal computer system fails to communicate with the sensors and components that control the heating process. It is typically caused by a malfunction within the main circuit board or a loose connection in the wiring that prevents the boiler from receiving the safety signals it needs to fire up.

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 →

Related fault codes

53:1View →F2View →

Related guides you might find useful

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →