What does the Alpha 20 fault code mean?

Your boiler is confused because it thinks it senses a flame when it shouldn't, or it can't correctly detect the flame it's working to produce.

How much does it cost to fix Alpha error code 20?

Typical repair cost for the Alpha 20 fault is £120-250 including labour.

Flame sensing fault - False flame detection / Flame detected but gas valve is not open

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

Work through these before the call-out.

Safety-critical — turn off, read this.

7 signs repair isn't worth it anymore.