warning Honeywell

Error Code bAt Lo

Low battery indicator that flashes for one to two months before batteries run out completely. Eventually stops flashing and stays on without flashing when batteries are almost completely dead.

? What Causes This

Batteries are running low or depleted. Non-alkaline batteries or batteries that have not been replaced annually.

How to Fix It

  1. Replace batteries with fresh AA alkaline batteries (Energizer recommended).
  2. If inserting new batteries within 20-30 seconds of removing old ones, reprogramming is not necessary.
  3. Replace batteries once a year as a precaution.
  4. If bAt Lo remains on after fresh batteries are installed, remove batteries, wait one hour, and install fresh alkaline batteries.

Source: page 8 of the official manual

From the manual

Manual page 8 — Honeywell error bAt Lo

This error code appears in:

Honeywell CT3355 Home Programmable Thermostat