Fault Code Lookup

HVAC Sales Master
E125
Control failed self-check / internal error / failed hardware
This code typically points to
  • Hardware error
  • Flame-sense circuit fault
  • Pin short

Next checks to confirm
  1. Cycle power
  2. Replace control if persistent

Escalation
Critical alert
Reset behavior
Clears 300 seconds after fault recovered.
Safety Critical
Immediate concern
Source
Lennox unit information doc 100027, p.11