F15 High

Johnson Starley F15 Fault Code

The Johnson Starley F15 fault code means: your boiler has stopped working because it has been manually reset too many times in a short window, suggesting an underlying fault that needs professional attention.. It appears on 2 Johnson Starley models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Reset occurs 5 times within 15 minutes
Typical repair cost £120-350 (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 F15 fault code

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

Source

Johnson Starley F15 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