Pr12 Low

Johnson Starley Pr12 Fault Code

Also written as PR12 — same fault.

The Johnson Starley Pr12 fault code means: your boiler is notifying you that its maximum power setting has been manually limited, often for efficiency or to match the specific size of your home.. It appears on 1 Johnson Starley model in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Parameter selection for reducing the rated net input
Typical repair cost £80-120 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Johnson Starley models that show the Pr12 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Johnson Starley Pr12 fault code information on this page is sourced and cross-checked against the official Johnson Starley service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026