AL74, AL79 High
Your boiler has detected an internal electronic error or a communication failure that is preventing it from heating your home.
Technical description: Reset the boiler. If the fault reoccurs, contact a heating engineer.
Typical repair cost: £120-350 (including labour)
DIY fix possible
Locate the mode selector switch on the front panelTurn the switch to the 'OFF/RESET' positionWait 30 seconds, then turn the switch back to either 'Heating' or 'Hot Water' mode
Protect yourself from future repair bills
A boiler cover plan would cover faults like AL74, AL79 — no call-out fees, no surprises.
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Parts commonly replaced
- Main Printed Circuit Board (PCB)
- Wiring Loom
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