⚠
warning Honeywell
Error Code Low battery icon
Battery power is low and needs replacement immediately.
? What Causes This
Batteries are depleted and thermostat is not wired to AC power.
✓ How to Fix It
- Replace batteries immediately with alkaline batteries.
- Ensure batteries are installed correctly.
- If issue persists, check C wire connection for AC power.
Source: page 2 of the official manual
From the manual
This error code appears in:
Honeywell T1 Pro Thermostat