E12 High
Your boiler is struggling to pump water around the system, often because the water pressure is too low or there is a blockage or air bubble preventing flow.
Technical description: Differential water flow switch is still open
Typical repair cost: £100-250 (including labour)
DIY fix possible
Check the pressure gauge on the front of the boiler and top it up to 1.5 bar if it is low.Ensure all radiator valves are fully open.Try bleeding your radiators to remove any trapped air.Reset the boiler to see if the fault clears.
Protect yourself from future repair bills
A boiler cover plan would cover faults like E12 — no call-out fees, no surprises.
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Parts commonly replaced
- Differential flow switch
- Circulation pump
- Central heating filter (cleaning)
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