BoilerFaultCodesYour boiler’s internal computer boards are having trouble communicating because they haven't been properly synced or configured to recognize each other.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: No valid appliance variant for display and/or electronics: Spare part case: Display and electronics changed at the same time appliance variant not re-set
What causes this fault?
This fault occurs when the boiler's internal control boards fail to recognize the specific model they are installed in, often because the 'identity code' has been lost or not set. This usually happens after a physical repair where both the main circuit board and the display screen were replaced simultaneously, leaving the system without a master record of its own configuration. Without this data, the boiler enters a safety mode because it doesn't know its own power rating or technical specifications.
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 F.70 — 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.