BoilerFaultCodesAlpha 51 Fault Code
The Alpha 51 fault code means: your boiler has lost its wireless connection with your thermostat or remote control, meaning they can no longer talk to each other to manage your heating.. It appears on 23 Alpha models in our database.
Technical description: Climatic RF communication fault
What causes the Alpha 51 fault?
This fault occurs when the invisible radio signal between your thermostat and the boiler is interrupted or lost entirely. The most common reason is that the batteries in your wall controller have died, but it can also be caused by new electronic devices or thick walls blocking the signal to the receiver. Effectively, the boiler has gone into a safety mode because it no longer knows whether your home is too hot or too cold.
DIY fix possible
Check the batteries in your wireless thermostat and replace them if they are low.Ensure the wireless receiver near the boiler is powered on and hasn't been blocked by metal objects.Try resetting the boiler and the thermostat to re-establish the wireless link.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Alpha models that show the 51 fault code
Click a model for the full fault code list and model-specific repair notes.
- C25 Xtraflame Repair: £100-200
- E-Tec Repair: £80-150
- E-Tec 24 Repair: £80-150
- E-Tec 28 Repair: £80-150
- E-Tec 33 Repair: £80-150
- E-Tec Plus Repair: £100-200
- E-Tec Plus 10 / 18 Repair: £0-180
- E-Tec Plus 24 Repair: £100-200
- E-Tec Plus 28 Repair: £100-200
- E-Tec Plus 33 Repair: £100-200
- E-Tec R Repair: £120-250
- E-Tec Regular Repair: £0-120
- Eco Repair: £90-200
- Eco 11 13 Repair: £0-180
- Evoke Repair: £80-150
- Evoke 10 / 18 Repair: £60-220
- FMK Repair: £0-180
- H25 Xtraflame Repair: £100-200
- Intec 28GS Repair: £100-200
- Intec 40GS2 Repair: £90-180
- Intec 50CS Repair: £100-200
- Intec2 25 28XE Repair: £80-180
- Intec2 30SE Repair: £100-250
Source
Alpha 51 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026