B7 257 — Internal error or control module problem

What does B7 257 mean?

This code indicates an internal error, possibly related to the boiler's control board or the Heat Control Module (HCM). The HCM or its connections may be defective.

• Defective control board.
• Defective Heat Control Module (HCM).
• Loose or incorrect connections to the HCM or control box.

Click steps to track your progress.

1. 1

   Reset the boiler by turning it off at the mains for at least 30 seconds and then back on.

2. 2

   If accessible, gently check that the Heat Control Module (HCM) is securely inserted.

3. 3

   If the error persists, contact a Gas Safe registered engineer, as internal components may require replacement.