BoilerFaultCodesYour boiler has detected a problem with how it controls the gas flow, meaning it cannot safely regulate the flame and has shut down as a precaution.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Fault with the gas modulator
What causes this fault?
This fault occurs when the boiler's main control board loses the ability to vary the amount of gas entering the burner, which is necessary to maintain the correct water temperature. The most common reason is an electrical failure in the solenoid coil that moves the gas valve, or a communication error from the circuit board itself. Because the system can no longer precisely control the size of the flame, it shuts down to ensure your home remains safe.
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.
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A boiler cover plan would cover faults like E4 — 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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