BoilerFaultCodesYour boiler has detected a communication problem between its main internal control board and the display interface.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: E-Combi EvoE-System EVOClas HE evo combiClas he evo system
What causes this fault?
This fault occurs when the boiler's internal computer brain loses its connection with the visual screen on the front panel. It is usually caused by a loose connecting wire, moisture getting into the electronics, or a component failure on one of the circuit boards. Because the two parts can no longer 'talk' to each other, the boiler shuts down as a safety precaution.
DIY fix possible
Turn the boiler power off at the fused spur switchWait for 60 secondsTurn the power back on and press the Reset button
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 703 — 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.