103 High
Your boiler has detected that water is not circulating properly through the system, often caused by a lack of water pressure or a blockage.
Technical description: All Boilers
Typical repair cost: £100-350 (including labour)
DIY fix possible
Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.If the pressure is low, use the filling loop underneath the boiler to top it up until the needle reaches 1.2 bar.Bleed your radiators using a radiator key to release any trapped air, then re-check the pressure gauge.
Protect yourself from future repair bills
A boiler cover plan would cover faults like 103 — no call-out fees, no surprises.
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Parts commonly replaced
- Central heating pump
- Pressure sensor
- Main heat exchanger (de-scaling)
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