BoilerFaultCodesYour boiler is struggling to heat up properly because the system isn't sensing the expected temperature increase when the unit is running.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Return sensor temperature rise incorrect (time taken for flow temperature to rise is too long.
What causes this fault?
This fault occurs when the boiler detects that the water returning to the unit isn't heating up as quickly as it should while the burner is active. The most common reasons are a blockage in the system or a failing pump that isn't moving the hot water away from the boiler fast enough. Sometimes, it can simply be a faulty sensor that is no longer reading temperatures accurately.
This issue is more common in autumn when heating systems are first turned on after a long summer break, often due to pump seizing or sludge build-up.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like 0A17 — no call-out fees, no surprises.
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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.
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