What does a solid red light on a trane xe80 furnace mean?

A solid red light on a Trane XE80 furnace typically indicates that the furnace is in a lockout mode due to a safety issue or malfunction. This could be caused by various factors, such as a blocked vent, a faulty pressure switch, or an ignition failure. To resolve the issue, it's advisable to check the furnace's air intake and exhaust for obstructions, reset the furnace, and consult the user manual or a professional technician if the problem persists.