BoilerFaultCodesYour boiler's computer brain has developed a software or hardware glitch and can no longer communicate with the rest of the system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Internal control unit error
What causes this fault?
This fault occurs when the boiler's main control board suffers an internal electronic failure or a software crash that prevents it from managing the heating process. It is often caused by aging electrical components on the circuit board or a sudden power surge that disrupts the unit's delicate memory. In some cases, loose wiring connections between the display screen and the main board can also trigger this communication breakdown.
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 E12 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Remeha Avanta Plus 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.