e12
Open fuse
This code typically points to
- Open control fuse
- 24V low-voltage short
Next checks to confirm
- Isolate 24V circuit short
- Replace fuse
- Check thermostat, outdoor contactor, accessories
Escalation
Control interruption / no heat
Reset behavior
Clears when fuse replaced and short corrected. Fault memory remains in L6F until cleared.
Urgent
Fix now