EH 258 — Burner control unit or HCM faulty

What does EH 258 mean?

The burner control unit or the Heat Control Module (HCM) is faulty. This indicates a problem with the core electronic components managing the boiler.

• Defective burner control unit.
• Defective Heat Control Module (HCM).
• Loose plug or damaged wiring of the burner control unit.

Click steps to track your progress.

1. 1

   Reset the boiler by power cycling it at the mains for 30 seconds, then turning it back on.

2. 2

   If accessible, gently check the connections and seating of the burner control unit or HCM.

3. 3

   Contact a Gas Safe registered engineer, as these critical components require expert diagnosis and possible replacement.