BoilerFaultCodesYour boiler has encountered an internal electronic communication error that is preventing it from running safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flashing fault code example (Internal error)
What causes this fault?
This fault occurs when the boiler's internal computer brain fails to communicate properly with the other sensors and components inside the unit. It is usually caused by a physical failure of the main circuit board or a loose connection in the internal wiring harness that prevents data from traveling through the system. Because the boiler cannot verify that it is operating safely, it stops running as a protective measure.
DIY fix possible
Press the 'Reset' button on the control panel once.Wait up to 15 minutes for the boiler to restart.If the code persists, do not attempt further repairs and contact a Gas Safe engineer.
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 E5 — 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.