How much does it cost to fix Johnson Starley error code 45?

Typical repair cost for the Johnson Starley 45 fault is £120-£220 including labour.

45 High

Johnson Starley 45 Fault Code

Q: What does the Johnson Starley 45 fault code mean?

Your boiler has detected an electrical fault with the internal sensor that monitors the safety of the exhaust gases, causing the system to shut down for protection.

The Johnson Starley 45 fault code means: your boiler has detected an electrical fault with the internal sensor that monitors the safety of the exhaust gases, causing the system to shut down for protection.. It appears on 10 Johnson Starley models in our database.

Technical description: Flue gas temperature sensor short circuit

Typical repair cost £120-£220 (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 45 fault code

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

Source

Johnson Starley 45 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