EA
Polarity of 115 V AC is reversed
This code typically points to
- Reversed line polarity to furnace or control module
- Poor unit ground
Next checks to confirm
- Review wiring diagram to correct polarity
- Verify proper ground
- Check/correct wiring
Escalation
Furnace fails to operate until corrected
Reset behavior
Clears after polarity/ground issue is corrected.
Urgent
Fix now