AL40 High
Your boiler has stopped working because the water pressure in the central heating system is too low.
Technical description: Check the system’s pressure and refill if necessary. Reset the boiler, if the fault reoccurs then you need to contact a heating engineer.
Typical repair cost: £0-120 (including labour)
DIY fix possible
Locate the filling loop (usually a silver braided hose with small valves underneath the boiler).Slowly open the valve(s) until you hear water entering the system and the pressure gauge reaches between 1 and 1.5 bar.Close the valves tightly and press the reset button on the boiler control panel.
Protect yourself from future repair bills
A boiler cover plan would cover faults like AL40 — no call-out fees, no surprises.
*Affiliate links — we may earn a commission at no extra cost to you. Prices shown are starting prices.
Parts commonly replaced
- Filling loop
- Pressure sensor
- Expansion vessel
*Affiliate links — we may earn a commission at no extra cost to you.