How much does it cost to fix Johnson Starley error code 30?

Typical repair cost for the Johnson Starley 30 fault is £90-160 including labour.

30 High

Johnson Starley 30 Fault Code

Q: What does the Johnson Starley 30 fault code mean?

Your boiler has stopped working because its internal thermometer has developed an electrical fault and can no longer monitor the water temperature accurately.

The Johnson Starley 30 fault code means: your boiler has stopped working because its internal thermometer has developed an electrical fault and can no longer monitor the water temperature accurately.. It appears on 10 Johnson Starley models in our database.

Technical description: Boiler flow temprature sensor short circuit

Typical repair cost £90-160 (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 30 fault code

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

Source

Johnson Starley 30 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