What does the Grant Lock-out (light on) fault code mean?

Your boiler has stopped itself from running as a safety precaution because the fuel failed to ignite properly.

How much does it cost to fix Grant error code Lock-out (light on)?

Typical repair cost for the Grant Lock-out (light on) fault is £120-250 including labour.

Check your external oil tank has enough fuel and the isolation valve is fully open

Burner not starting - fuel and electricity supplies present. Press the reset button on the burner control box.

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.

Lockout fault with a reset-needed pattern.

Safety-critical — turn off, read this.