If the thermostat is unable to control your system due to a battery problem, the thermostat will enter Error Mode. In this condition, the thermostat flashes E1 or E2 on the LCD display, and shuts off your system. To correct this problem, replace the batteries with 2 new AA alkaline batteries, even if you have recently replaced them.
Remove the battery, hold any key, then replace the battery again. You will need to reprogram your thermostat and confirm normal operation. If Error Mode returns, please contact us for further information.