How much does it cost to fix Johnson Starley error code E34?

Typical repair cost for the Johnson Starley E34 fault is £100-280 including labour.

E34 High

Johnson Starley E34 Fault Code

Q: What does the Johnson Starley E34 fault code mean?

Your boiler has detected that the electricity supply coming into the unit is too low to operate safely, causing it to shut down to protect its components.

The Johnson Starley E34 fault code means: your boiler has detected that the electricity supply coming into the unit is too low to operate safely, causing it to shut down to protect its components.. It appears on 7 Johnson Starley models in our database.

Technical description: Low power supply lockout

Typical repair cost £100-280 (including labour)

DIY fix possible

Check if there is a power cut or brownout in your local area.Ensure the boiler is plugged into a dedicated socket or fused spur and not an extension lead.Reset the boiler once you are certain the mains power supply is stable.

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Johnson Starley models that show the E34 fault code

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

Source

Johnson Starley E34 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