BoilerFaultCodes 25 High
Alpha 25 Fault Code
The Alpha 25 fault code means: your boiler has shut down because the internal exhaust gases are getting too hot too quickly, which is usually a sign of a blockage or a circulation problem.. It appears on 19 Alpha models in our database.
Technical description: Rapid temperature rise of flue sensor
Typical repair cost £120-£350 (including labour)
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 25 fault code
Click a model for the full fault code list and model-specific repair notes.
- 240XE Repair: £120-220
- C25 Xtraflame Repair: £150-350
- E-Tec Repair: £250-450
- E-Tec 24 Repair: £250-450
- 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 24 Repair: £200-350
- E-Tec Plus 28 Repair: £200-350
- E-Tec Plus 33 Repair: £200-350
- Eco Repair: £150-250
- Eco 11 13 Repair: £120-£350
- H25 Xtraflame Repair: £150-350
- Intec 24GS Repair: £150-300
- Intec 28GS Repair: £150-350
- Intec 40GS2 Repair: £150-300
- Intec 50CS Repair: £150-350
- Intec2 25 28XE 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 27 April 2026