D6 Error //top\\ — Viessmann

Viessmann D6 Error: Causes, Diagnosis, and Complete Fix Guide

Step 4: Call a Professional

1. Boiler calls for heat.
2. Fan runs, gas valve opens.
3. Ignition spark occurs (you might hear clicking).
4. Flame establishes briefly, then extinguishes.
5. Control unit tries 2–4 times, then locks out with D6.

Safety first:

⚠️ Always turn off the boiler’s power supply at the fused spur or circuit breaker before touching any internal components.

other codes

Does your boiler display alongside the D6, or did it start making strange noises before the lockout? Viessmann Fault Code Checker viessmann d6 error