Sensor is flashing, does that mean new batteries need to be installed?

Hi,

Here’s what the user manual says about a flashing temperature indicator:

Outdoor temperature is flashing or showing dashes:

Flashing of the outdoor temperature may be an indication of wireless interference.• Make sure the A-B-C switch in the battery compartments of both the display and sensor are switched to the same letter. You may choose A, B or C; but both units must match to sync up. Sometimes changing to a different channel can help

If it were the batteries more likely there would be no outdoor sensor reception signal bars showing, rather than the temperature indicator flashing, but you could always try changing them and see what happens.