E40 Emergency
Your boiler has switched off because there is too much water pressure in the system, which can put unnecessary strain on the internal seals.
Technical description: Water pressure too high
Typical repair cost: £80-200 (including labour)
DIY fix possible
Check that the filling loop (the flexible silver hose) is tightly closed at both ends.Locate a radiator and use a bleed key to release water into a jug/towel until the pressure gauge on the boiler drops to 1.5 bar.Restart the boiler once the pressure has stabilized.
Protect yourself from future repair bills
A boiler cover plan would cover faults like E40 — no call-out fees, no surprises.
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Parts commonly replaced
- Filling loop valve
- Expansion vessel
- Pressure relief valve
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