LO means Low temperature, and not low battery – so no worries! Low battery sign is usually "Lo batt" in a corner of a display. LO is shown in the display where the temperature is normally displayed. The temperature sensed by the thermostat is lower than the 40 F (4 C) lower limit of the thermostats display range.
Why the thermometer shows 'LO' from time-to-time?
It is standard practice for the majority of digital thermometers to display a "LO" sign when turning the device on. This means "LOW TEMPERATURE". This is because these types of thermometers are made to measure Body Temperature, so when outside the body, the temperature is usually LOWER.
How do I fix the LO on my thermometer?
The 'Lo' or 'Hi' indications on the display mean that the temperature cannot be measured because the temperature is outside the temperature range. Press the on/off button to switch off the thermometer. Check if it is correctly positioned, press the on/off button again to switch it on, and re-start the measurement.