High Lockout
50:0 on Viessmann Vitodens 200-W

Your boiler's computer screen and main control board are having trouble communicating with each other.

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

Alternative control (automatic adjustment upon recognition of the operating interface)

What causes this fault?

This fault occurs when the boiler's internal computer brain loses its connection with the display screen on the front of the unit. The most common reason is a loose or damaged data cable connecting the two parts, or an electronic failure within the display module itself. Because the components can no longer 'talk' to each other, the boiler stops working as a safety precaution.

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

50:1View →58:0View →F0View →

Related guides you might find useful

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

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 →