BoilerFaultCodesAlpha 0A17 Fault Code
The Alpha 0A17 fault code means: your boiler is struggling to detect the expected temperature increase in the water flowing back to it, likely due to a circulation or sensor issue.. It appears on 3 Alpha models in our database.
Technical description: Return sensor temperature rise incorrect. The time taken for the return temperature to rise is too great.
What causes the Alpha 0A17 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
Search the official register for a qualified engineer in your area.
Gas Safe Register →Alpha models that show the 0A17 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Alpha 0A17 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026