High
E03 on Johnson Starley Quantec 24S

Your boiler has temporarily shut itself down because it got too hot, and it needs a manual reset to start working again.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

Lockout: high limit temperature protection. Needs a manual reset.

From this model's manual
Verified against the Johnson Starley/Johnson Starley Quantec C System installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

E01View →E02View →E04View →

All 3 fault codes on the Quantec 24S

Seeing a different code? Every code this model can display, in one place.

F37F40

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