Goodman furnace: Open Auxiliary Input (EF)
Professional repair
What does EF mean on a Goodman GMVM97 furnace? The auxiliary input circuit is open — an external safety device wired into AUX (condensate overflow switch, etc.) has tripped.
GOOD NEWS: THE FIRST CHECKS ARE FREE AND TAKE MINUTES.
Try these first — in this order
Check the condensate pump/float switch — empty and reset.
If no external device tripped, the circuit needs tracing.
What causes it (in order of likelihood)
- Tripped external safety (often a full condensate pan/float switch) DIY-CHECKABLE
Parts for this code
No specific part number is verified for this code — it typically points at wiring, power, a blown fuse, or communication between components rather than one standard replacement part. If your diagnosis does land on a replaceable component, match its part number against your model's parts list before ordering.
Applies to
GMVM97
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 GMVM97 Service Manual, p.64
Last verified 2026-07-06 · how we verify
Related Goodman fault codes
These codes use the same modulating furnace (gmvm97) — dual 7-segment display system.
| Pattern | Meaning |
|---|---|
| b0 | Blower Motor Not Running (b0) |
| EE | Improper Wiring to the Furnace (EE) |
| b1 | Blower Communication Error (b1) |
| EC | Inducer Motor Overcurrent (EC) |