Medium
51 on Alpha E-Tec 33

Your boiler is struggling to talk to your wireless thermostat, meaning it doesn't know when to turn your heating on or off.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Climatic RF communication fault. Error between communication of the Climatic transmitter and boiler receiver

From this model's manual
Verified against the Alpha E Tec Regular installation & service manual, page 47.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check if the batteries in your wireless room thermostat are flat and replace them if necessary.Ensure the thermostat is within range of the boiler and has not been moved behind a large metal object or thick wall.Follow your specific model's manual instructions to re-sync or 'pair' the thermostat to the boiler receiver.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like 51: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related guides you might find useful

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →