Generac home standby generators

Generac undervoltage alarms 1900–1906

These alarms report that the generator is not producing the voltage expected by its controller. They identify a condition—not a specific failed part.

Confirm this guide applies

The official Generac article reviewed for this guide covers U.S. and Canadian Next Generation Series 10–28 kW air-cooled home standby generators and Guardian Series 10–26 kW air-cooled home standby generators from 2017 to present. It addresses codes 1900 through 1906 shown by the generator control panel. Verify the complete model, serial number, controller, region, and current owner manual before acting.

What the alarm means

The controller detected prolonged undervoltage or a sudden loss of generated voltage. Generac lists several possible categories, including fuel supply or fuel-selection problems, circuitry, firmware, and voltage production. A code such as 1902 does not by itself prove that an AVR, controller, wiring component, or any other individual part failed.

Record before clearing anything

Photograph the exact four-digit code and red status LED.
Record the complete model, serial number, installation year, controller display, fuel type, and LP tank level if applicable.
Note whether the unit was exercising or carrying a house load, the weather, and anything that changed immediately before the alarm.
Keep the alarm present for the service provider when practical; repeated clearing can erase useful context.

Safe owner observations

Stay outside the enclosure and use only the owner-manual checks for your exact unit.

Confirm that the external fuel supply is available. For LP systems, Generac advises having more than 30% in the tank.
Look from a safe distance for snow, ice, or debris blocking exterior airflow; do not remove panels or reach into the unit.
On applicable Guardian models only, compare the controller fuel-selection setting with the installed fuel, following the exact owner manual. Next Generation fuel conversion is an installer setup handled through Generac Field Pro.
If the alarm occurred during an outage, remove the house load only by following Generac’s official shutdown procedure before any restart.

About clearing and restarting

Generac’s support article allows clearing the alarm and attempting a manual start after the safe checks. Do this only once, with the generator not under load, and only by the instructions for the exact controller. Never repeatedly reset a returning alarm or start the generator under load.

Stop and call an authorized service dealer

The 1900–1906 alarm returns, the unit will not produce stable power, or the safe observations do not reveal an obvious external cause.
You smell fuel or see smoke, fire, damaged wiring, liquid leakage, severe ice, or hear abnormal mechanical noise.
Diagnosis would require opening the enclosure, measuring live voltage, changing wiring, fuel pressure, a fuel jet, firmware, the AVR, or controller.
The system is newly installed or the issue could involve installation, conversion, warranty, or utility fuel supply.

Do not open the generator enclosure, probe live circuits, adjust gas pressure, change fuel jets, replace control parts, or bypass a transfer switch or safety device. Those are technician tasks.

Official source and review scope

Technical meaning and applicability are summarized from Generac’s official support article “Undervoltage, error codes 1900-1916,” dated August 26, 2025. This page was reviewed September 18, 2026. Always use the current manual for the exact model and serial number.

Read the official Generac undervoltage article

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