My furnace is not running. Two red lights are blinking meaning "pressure open". What does this mean and how do you fix it?

My gas furnace is flashing two red lights saying "pressure open". What is this and how can I fix it? Do I need a professional?

One of your pressure switches is not working. Open the front of the unit, at the burners, and look for a round disc with a plastic or rubber tube. Make sure it is unobstructed. You may have also have a partially obstructed vent pipe, especially if you have a 90% heater. Your inducer fan may not be working. It supplies air pressure to close the switch. If you know nothing about heaters, suggest you get someone to look at it.