How much does it cost to fix Johnson Starley error code 43?

Typical repair cost for the Johnson Starley 43 fault is £120-210 including labour.

43 High

Johnson Starley 43 Fault Code

Q: What does the Johnson Starley 43 fault code mean?

Your boiler has detected an electrical fault with the internal sensor that monitors the temperature of the air returning to the unit, causing it to shut down for safety.

The Johnson Starley 43 fault code means: your boiler has detected an electrical fault with the internal sensor that monitors the temperature of the air returning to the unit, causing it to shut down for safety.. It appears on 4 Johnson Starley models in our database.

Technical description: Return air temperature short circuit. Temperature sensor shorted to. Check wiring connections not shorting to earth. Check sensor resistance.

Typical repair cost £120-210 (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 43 fault code

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

Source

Johnson Starley 43 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