81W03 – CONTROL BOARD*

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.

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• 100973-01
• 100973-02
• 10097302
• 17W70
• 17W701
• 75M17
• 75M1701
• 78M47
• 78M4701
• 81W0301

Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.

Fits these models

• G40UH-48B-090-15