BoilerFaultCodesPotterton B(2) Fault Code
Also written as B2 — same fault.
The Potterton B(2) fault code means: your boiler's pilot light is likely going out because a safety sensor has lost its connection, preventing the unit from staying lit.. It appears on 3 Potterton models in our database.
Technical description: Loose thermocouple connection into control valve
What causes the Potterton B(2) fault?
This fault occurs when the safety sensor that detects the pilot light fails to send a clear signal back to the main gas valve. The most common reason is that the physical connection between the thermocouple and the control box has vibrated loose or become corroded over time. Because the boiler can no longer verify that a flame is present, it shuts off the gas supply as a safety precaution.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Potterton models that show the B(2) fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton B(2) 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