Before replacing the board, count the LED blinks — the error code tells you what actually failed. Sometimes it’s a $15 fuse, not a $140 board.
81W03 – CONTROL BOARD*
$225.16
Lennox 81W03 ignition control board. OEM replacement for Lennox furnaces. Manages ignition sequence and heating cycles. Replaces 75M17 and 78M47.
Mon–Fri 10 am – 7 pm | Sat 10 am – 3 pm | In-Store Pickup Only
Description
If your furnace won’t ignite, shows error codes, or the blower won’t start, the control board controls all of it. The 81W03 is a Lennox OEM ignition control board that manages the ignition sequence and heating cycle timing. Direct replacement for earlier Lennox board revisions.
Specs: OEM Lennox ignition control board, LED diagnostics
Replaces: 100973-01, 100973-02, 17W70, 75M17, 78M47
Fits: Lennox furnaces using 81W03-series control boards
Need help? See our Furnace Not Heating Guide.
In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.
