BoilerFaultCodesVokera A42 Fault Code
The Vokera A42 fault code means: your boiler has detected that the water pressure inside your heating system is too low to operate safely, so it has shut down to protect itself.. It appears on 3 Vokera models in our database.
Technical description: Fill the system
DIY fix possible
Locate the filling loop (a flexible metal or silver braided hose) underneath the boiler.Open the valves at both ends of the loop to allow water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Firmly close both valves and check for any leaks.
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Vokera models that show the A42 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera A42 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 7 July 2026