How much does it cost to fix Johnson Starley error code F-15?

Typical repair cost for the Johnson Starley F-15 fault is £0-120 including labour.

F-15 Medium

Johnson Starley F-15 Fault Code

Q: What does the Johnson Starley F-15 fault code mean?

Your boiler has been manually reset too many times in a short window, causing the system to lock itself out for safety.

Also written as F15 — same fault.

The Johnson Starley F-15 fault code means: your boiler has been manually reset too many times in a short window, causing the system to lock itself out for safety.. It appears on 1 Johnson Starley model in our database.

Technical description: Reset occurred 5 times within 15 minutes

Typical repair cost £0-120 (including labour)

DIY fix possible

Turn the electrical power supply to the boiler off at the fused spur switch.Wait for at least 20 minutes without touching any buttons to allow the internal timer to clear.Switch the power back on and see if the boiler resumes normal operation without further resets.

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Johnson Starley models that show the F-15 fault code

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

J32 System ET Repair: £0-120

Source

Johnson Starley F-15 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 27 April 2026