Trane furnace codes are series of blinking red lights that alert the owner to various problems. The owner can check the owner's manual to determine the specific problem once the code has been deciphered.
Two flashes signals that the system is locked out and has exceeded its normal number of retries. If there are three flashes, there is a error in the draft pressure. Four flashes indicates a problem with the open temperature limit circuit, and five flashes shows that the furnace has sensed a flame where there should be none. If there are six flashes, the unit is experiencing poor grounding or low voltage.