E8
High-stage pressure-switch circuit is closed at start of heating cycle; furnace operates in low stage only
This code typically points to
- High-stage pressure-switch contacts sticking
- Short in pressure-switch circuit wiring
Next checks to confirm
- Replace high-stage pressure switch
- Repair short in wiring
Escalation
Furnace fails to operate on high stage and runs low stage only
Reset behavior
Clears after switch/wiring fault is corrected.
Service Soon
Schedule repair