BoilerFaultCodesYour boiler has stopped working because it cannot properly detect the flame it needs to stay lit safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Burner blocked - Internal error (Check ionisation electrode and leads/flue gas system)
What causes this fault?
This fault occurs when the boiler's internal sensors fail to confirm that a steady flame has been established, causing the system to shut down for safety. The most common reason is a worn or carbon-coated detection probe that can no longer 'see' the flame, though it can also be caused by a blockage in the air supply or chimney preventing clean combustion.
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 E5 — no call-out fees, no surprises.
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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.
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