BoilerFaultCodesAlpha 75 Fault Code
The Alpha 75 fault code means: your boiler's internal thermometers are misreading the temperature or have failed, which has caused the system to shut down for safety.. It appears on 13 Alpha models in our database.
Technical description: Return/flow sensor fault from possible failure of one or both sensors
What causes the Alpha 75 fault?
This fault occurs when the boiler's control board detects that the temperature sensors (NTC thermistors) are sending conflicting information or no signal at all. The most common reason is a physical failure of the internal sensor probes, but it can also be caused by loose wiring or mineral buildup on the sensors preventing them from reading heat levels accurately.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Alpha models that show the 75 fault code
Click a model for the full fault code list and model-specific repair notes.
- E-Tec Repair: £120-220
- E-Tec 24 Repair: £120-220
- E-Tec 28 Repair: £120-220
- E-Tec 33 Repair: £120-220
- E-Tec Plus Repair: £120-220
- E-Tec Plus 10 / 18 Repair: £120-190
- E-Tec Plus 24 Repair: £120-220
- E-Tec Plus 28 Repair: £120-220
- E-Tec Plus 33 Repair: £120-220
- E-Tec R Repair: £150-250
- E-Tec, E-Tec Plus, Evoke Repair: £120-210
- Evoke Repair: £150-250
- Evoke 10 / 18 Repair: £90-160
Source
Alpha 75 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