BoilerFaultCodesPotterton A15 Fault Code
The Potterton A15 fault code means: your boiler has stopped working because the water pressure in the central heating system is too low or a sensor has failed.. It appears on 1 Potterton model in our database.
Technical description: CH pressure loss/pressure sensor faulty. Check/replenish CH system pressure. Find leaks. Check/replace pressure transmitter and cable.
What causes the Potterton A15 fault?
This fault occurs when the internal sensor detects that the water pressure has dropped below the minimum level required to operate safely. The most common reason is a slow leak somewhere in your radiators or pipework, but it can also happen if the expansion vessel has lost its air charge and can no longer stabilize the pressure.
This issue is more frequent in autumn when homeowners first turn their heating back on after summer, as the change in temperature can reveal small leaks or failed seals.
DIY fix possible
Check the pressure gauge on the front of the boilerIf the pressure is below 1.0 bar, locate the filling loop (braided silver hose) under or near the boilerSlowly open the valves to top up the water until the gauge reads between 1.0 and 1.5 bar, then close them tightly
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Gas Safe Register →Potterton models that show the A15 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton A15 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