BoilerFaultCodesYour boiler has experienced a serious software or electrical error and has locked itself for safety, meaning it cannot provide heat or hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Volatile lockout
What causes this fault?
This fault occurs when the boiler's internal computer, the Printed Circuit Board, suffers a critical failure or receives abnormal electrical signals it cannot process. The most common reasons are a malfunctioning circuit board, a faulty ignition system that is confusing the controls, or a sudden electrical surge that has damaged the sensitive internal components.
DIY fix possible
Press and hold the 'Reset' button for five secondsWait for the indicator light to stop flashing or change to a steady lightIf the boiler refires, check that your thermostat is calling for heat
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 Fast flash / Off — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch Greenstar 24i Junior is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.