Goodman furnace LED off: No LED Signal
Professional repair
Why is the diagnostic light off on my Goodman furnace? Per the Goodman service manual, an internal control failure or a blown board fuse will cause the diagnostic LED to provide no signal. It can also simply mean the board isn't getting power.
Before you touch anything: the six signs that mean stop troubleshooting and call a pro →
GOOD NEWS: THE FIRST CHECKS ARE FREE AND TAKE MINUTES.
Try these first — in this order
Check the breaker, door switch, and board fuse — about 10 minutes.
Before replacing a board, have a technician find what killed it (shorts often repeat). DIY part cost: $80–180 — a pro visit for this class of fault typically runs $150–350.
What causes it (in order of likelihood)
- Tripped breaker or blower-door switch not engaged (check first) DIY-CHECKABLE
- Blown fuse on the control board (official check item) DIY-CHECKABLE
- Failed integrated control board TECH
Parts referenced by this code
Always match parts against your model's parts list — part numbers vary within a series.
Questions about this code
Why is the diagnostic light off on my Goodman furnace?
Per the Goodman service manual, an internal control failure or a blown board fuse will cause the diagnostic LED to provide no signal. It can also simply mean the board isn't getting power.
How do I fix Goodman furnace LED off?
You can confirm the thermostat has power and the blower door looks fully closed. Checking breakers, the door switch, the board fuse, or the board itself is technician work.
How much does it cost to fix Goodman furnace LED off?
Cost depends on why the board has no signal. A power-supply issue, a blown fuse, and a failed control board are very different repairs, and a technician should find any short first.
Applies to
GMS8 · GDS8 · GHS8 · GMSS96 · GMH8 · GDH8
Different Goodman generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.
Verified against Goodman GMS8/GDS8/GHS8 Service Manual (RS6612006), p.42-43 — “will cause the diagnostic LED to provide no signal”
Last verified 2026-07-06 · page updated 2026-10-03 · how we verify
Related Goodman furnace codes
These codes use the same single red led — flash codes system.
| Pattern | Meaning |
|---|---|
| 1 flash | Ignition Lockout — Flame Not Established After 3 Tries |
| 2 flashes | Pressure Switch Stuck Closed |
| 3 flashes | Pressure Switch Stuck Open |
| 4 flashes | Open Primary Limit Switch |