Fault Code Lookup

HVAC Sales Master
E206
Gas valve second-stage relay failure
This code typically points to
  • Stage-2 relay failure on control

Next checks to confirm
  1. Confirm furnace only runs in first stage on call
  2. Replace control if stage 2 cannot be restored

Escalation
Furnace operates on first stage for remainder of demand
Reset behavior
Clears after fault recovers.
Service Soon
Schedule repair
Source
Lennox unit information doc 100027, p.13