BoilerFaultCodesVokera AL26 Fault Code
The Vokera AL26 fault code means: your boiler has sensed that the water returning to it is too hot, which suggests that the heat is not being effectively pumped away through your radiators.. It appears on 8 Vokera models in our database.
Technical description: Return temperature too high flow sensor temperature).
What causes the Vokera AL26 fault?
This fault occurs when the water coming back into the boiler is nearly as hot as the water going out, which prevents the heat exchanger from cooling down. The most common reason is a blockage in the system or a failing pump that isn't pushing the water through your radiators quickly enough. It can also be caused by a build-up of sludge or debris trapped in the boiler's internal filter.
This issue often surfaces during the first cold spell of autumn when the heating is turned back on after months of inactivity, which can cause the pump to seize.
DIY fix possible
Check that all radiator valves are fully openEnsure the central heating bypass valve is not closedTurn the boiler off and on again to see if the pump restarts
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Gas Safe Register →Vokera models that show the AL26 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera AL26 fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026