BoilerFaultCodesAlpha 25 Fault Code
The Alpha 25 fault code means: your boiler is shutting down because it senses that the water inside is heating up far too quickly, often due to a blockage in the system or a pump failing to move the water around.. It appears on 16 Alpha models in our database.
Technical description: Rapid primary flow temperature increase
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Alpha models that show the 25 fault code
Click a model for the full fault code list and model-specific repair notes.
- 240XE Repair: £120-220
- Cd50s Cd70s Repair: £180-350
- E-Tec 28 Repair: £250-450
- E-Tec 33 Repair: £250-450
- E-Tec Plus Repair: £200-350
- E-Tec Plus 10 / 18 Repair: £250-450
- E-Tec Plus 28 Repair: £200-350
- E-Tec Plus 33 Repair: £200-350
- E-Tec S Repair: £250-450
- Eco Repair: £120-250
- Eco 11 13 Repair: £120-250
- Intec 40GS2 Repair: £150-300
- Intec 50CS Repair: £150-350
- Intec S Repair: £150-300
- Intec2 25 28XE Repair: £150-300
- SY9 24 Repair: £150-300
Source
Alpha 25 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 7 July 2026