BoilerFaultCodesWhat the manual says
Manufacturer manualHEAT EXCHANGER OVERHEAT
What causes this fault?
This fault occurs when the boiler tries to ignite three times but fails to detect a stable flame. The most common reasons include a lack of gas reaching the burner, dirty ignition components that can't create a spark, or a faulty sensor that cannot 'see' the flame even if it has lit.
This fault is more common during extreme cold spells because the gas supply can fluctuate or the external condensate pipe can freeze, causing the boiler to fail the ignition sequence.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Avoid the next call-out bill
A cover plan would handle faults like L9: no call-out fees, no surprise bills.
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