Viessmann Vitodens 100-W fault 62

What it means

Burner in a fault state because the high limit safety cut-out has tripped, typically due to overheating or insufficient flow.

Likely causes

1. Inadequate heat transfer
2. High limit safety cut-out has responded

Where to start

1. Verify control unit issues a heat demand; if not, increase set value and ensure heat transfer.
2. Verify fan starts; if not, fault 59/457 - check fan connecting cables and fan power supply.
3. Verify ignition occurs; if not, fault 359 - check ignition module control voltage and gas supply.