E25 High
Your boiler is heating up faster than the water can move away, which usually means something is blocking the flow or the pump isn't circulating water correctly.
Technical description: Flow temperature increased too quickly – check water circulation
Typical repair cost: £150-£450 (including labour)
DIY fix possible
Check that at least two or three radiator valves are fully open.Ensure the central heating bypass valve is not closed.Check for any visible leaks around the boiler or pipework.Try resetting the boiler to see if the circulation clears.
Protect yourself from future repair bills
A boiler cover plan would cover faults like E25 — no call-out fees, no surprises.
*Affiliate links — we may earn a commission at no extra cost to you. Prices shown are starting prices.
Parts commonly replaced
- Circulation Pump
- Flow Temperature Sensor (NTC)
- Main Heat Exchanger (if scaled or blocked)
*Affiliate links — we may earn a commission at no extra cost to you.