What does the Johnson Starley E03 fault code mean?

Your boiler has switched itself off because it has reached an unsafe temperature to prevent damage to the internal components.

How much does it cost to fix Johnson Starley error code E03?

Typical repair cost for the Johnson Starley E03 fault is £120-350 including labour.

Check that all radiator valves are fully open to allow water to circulate.

Overheat lockout

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

Each noise points to a different fault.

Sludge build-up — needs flushing, not bleeding.

Work through these before the call-out.