Trane Furnace Error Code Green/Red LEDs on continuously

When both the green and red LEDs on a Trane furnace control board glow steadily at the same time without flashing, it indicates either an open fuse on the control board or an internal failure of the control board itself. This is a board-level electrical fault rather than a system operational fault. The furnace will not run normally in this state, and the condition requires inspection of the board fuse and the board's internal components.

A standard power reset will generally not clear this fault if an internal control board failure is the cause, since the board itself is not functioning correctly. If a blown fuse is the cause, resetting power without replacing the fuse will not restore operation either. The underlying issue, whether a short circuit or a failed board, must be corrected before the furnace will return to normal operation.

If only the fuse and wiring need attention, repair costs are typically in the range of $75 to $200 depending on labor rates and any damaged wiring. If the control board requires replacement, costs generally range from $300 to $700 or more depending on the specific board model, labor, and regional pricing. Getting a diagnostic assessment from a technician will clarify which component is at fault before committing to a repair.

If the cause is a blown fuse on the control board, a knowledgeable DIYer can replace the fuse after first identifying and correcting any short circuit in the low-voltage wiring. However, if the control board itself has an internal failure, replacement of the entire board is required, which involves working inside the furnace cabinet and handling electrical components. If you are not comfortable with electrical diagnostics, a licensed HVAC technician should perform the repair.

No. When the Trane furnace displays this LED condition, the control board is not able to manage furnace operations reliably. Running the furnace with a failed control board or an open fuse condition creates a risk of uncontrolled operation or no safety monitoring. The furnace should remain off until the fault is diagnosed and repaired.