25E High
Your boiler has detected that the water inside the main heating unit has frozen, which is preventing the system from operating to avoid damage.
Technical description: Main heat exchanger frozen
Typical repair cost: £0-120 (including labour)
DIY fix possible
Check if the condensate pipe (the plastic pipe leading outside) is frozen and thaw it with warm water or a heat pack.Increase the room thermostat temperature and wait for the ambient heat inside the house to naturally thaw the unit.Reset the boiler once the system has thawed completely.
Protect yourself from future repair bills
A boiler cover plan would cover faults like 25E — no call-out fees, no surprises.
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Parts commonly replaced
- Condensate pipe insulation
- Main heat exchanger
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