BoilerFaultCodesYour boiler has shut itself down as a safety precaution because one of its internal protection systems has detected a fault.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The safety devices have been activated (lockout)
What causes this fault?
This fault occurs when the boiler’s safety sensors detect that the system has exceeded its safe operating temperature or experienced a critical electrical interruption. It usually triggers because water is not moving through the heat exchanger quickly enough to cool it down, or because a safety component itself has failed. The most common reasons include a failing circulation pump, a blockage in the pipework, or a faulty internal limit thermostat.
This issue is more frequent during the first cold snap of autumn, when pumps that have been idle over summer often seize up when first called upon for heating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E17 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
Affiliate links — we may earn a commission at no extra cost to you.