37 High
Your boiler has detected that there is not enough water in the heating system to operate safely, causing it to shut down.
Technical description: Low system water pressure
Typical repair cost: £0-120 (including labour)
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Slowly open the small valves on the filling loop until you hear water moving.Watch the pressure gauge and close the valves once the needle reaches between 1 and 1.5 bar.
Protect yourself from future repair bills
A boiler cover plan would cover faults like 37 — no call-out fees, no surprises.
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Parts commonly replaced
- Filling loop
- Pressure sensor
- Expansion vessel
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