BoilerFaultCodesPotterton A05 Fault Code
The Potterton A05 fault code means: your boiler's electronic brain has detected an internal safety error and has shut down for protection.. It appears on 1 Potterton model in our database.
Technical description: Safety relay failure (in boiler control). Switch OFF/ON - press RESET. Replace boiler control Part No. 5107535
What causes the Potterton A05 fault?
This fault occurs when the boiler's internal safety checks detect a failure in the electronic components that manage gas flow and ignition. Essentially, a critical safety switch inside the control board has become stuck or damaged, preventing the boiler from firing up safely. Because the system can no longer verify that it is safe to operate, it shuts down to prevent any potential hazards.
DIY fix possible
Locate the power switch for the boiler and turn it OFFWait for 30 seconds, then turn the power back ONPress the 'RESET' button on the boiler control panel
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Potterton models that show the A05 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton A05 fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026