Generac · Generator Minor

1900 — Undervoltage

Alarm 1900 is "Undervoltage" — the generator output voltage dropped below the acceptable threshold, so the controller shut down to protect connected loads. It is not the loss-of-utility/outage signal (that is a transfer event, not alarm 1900).

Keep using it?
Yes — fix when convenient
DIY difficulty
Easy
Verified against
generac.com ↗

How to fix it

  1. Reduce/disconnect loads and retest.
  2. Check engine speed/governor and fuel delivery.
  3. Have a Generac dealer test the voltage regulator and windings if it persists.

Why it happens

Typical signs: 1900 / Undervoltage in the alarm log · Generator runs but output voltage is low · Shutdown shortly after starting under load

  • Voltage regulation or excitation fault Failing voltage regulator, rotor/stator winding issue, or brushes.
  • Engine speed too low under load Low RPM drags output voltage down; check governor/fuel.
  • Overload A load larger than the generator can support can pull voltage down.

More Generac generator codes

1100 1100 — Overcrank (Engine Failed to Start) 1300 1300 — Low Oil Pressure Shutdown 1501 1501 — RPM Sense Loss 1505 1505 — Overcrank (Variant — Try Again) 1600 1600 — Underspeed 1800 1800 — Overvoltage

All Generac codes → All generator codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: generac.com.