Read the manual thoroughly and understand all of the instructions, cautions, and warnings before using this equipment. If any section of the manual is not understood, contact your nearest authorized dealer, or contact Generac Customer Service at 1-888-436-3722 (1-888-GENERAC), or www.generac.com with any questions or concerns. 

 

Undervoltage: Error Codes 1900-1916

 

Environment

• Generac Next Generation Series 10-28 kW air-cooled standby generators
• Generac Guardian Series 10-26 kW air-cooled standby generators (2017 to present)

Note: The term "error code" is used interchangeably with 'alarm code,' 'fault code,' 'fault alarm' and similar terminology. Error code applies to all such terminology. 

Overview

• Error codes: 1900-1906
• LED Indicator: Red
• Fault: UNDERVOLTAGE
• Issue: The generator is not producing proper voltage. This could result from prolonged under voltage or sudden voltage loss.
• Cause: Often linked to fuel supply/selection issues, circuitry, firmware, or voltage production. While basic checks, like verifying fuel supply/selection and restarting can be attempted, the electrical nature of this issue typically requires advanced diagnosis by a Generac Independent Authorized Service Dealer (IASD)

What can I do?

• Your options are limited beyond performing basic troubleshooting checks on components and verifying that everything appears normal.
• You can attempt to clear the alarm and manually restart the unit: How Do I Clear an Error or Alarm Code On My Home Standby Generator?
• Sometimes, clearing the alarm and attempting to restart the unit is all that is needed, as the alarm may be a one-time occurrence that does not indicate a persistent issue.

Note: Never start a generator while under load. See the scenario-based considerations below for troubleshooting in an outage/utility power failure.

When should you contact a Generac Independent Authorized Service Dealer (IASD)?

• If issues persist after performing the checks and attempting to restart, contacting a Generac IASD for diagnosis is strongly recommended. 

 

General troubleshooting steps

Fuel supply or fuel selection:

The undervoltage error code can occur due to fuel selection or supply issues. Air-cooled home standby generators are designed to operate on either Liquid Propane (LP) or Natural Gas (NG) and can be converted in the field.

Note: The below steps only apply to Guardian series generators. For Next Generation series generators, fuel conversion takes place in the Field Pro app during initial installation: How Do I Perform a Fuel Conversion on My Air-Cooled Home Standby Generator?

Fuel conversion requires correct fuel jet positioning and proper fuel type selection in the controller. If the jet position and fuel type settings in the controller do not align with the actual fuel source, it can disrupt operation, affect voltage output, and potentially trigger an undervoltage alarm.

• Verify that the correct fuel source has been selected in the controller (NG or LP).
  • How do I verify the correct fuel selection is selected for my generator?
• Verify the fuel jet position is correct. 
• Note that fuel jet positioning is typically a only a concern during new installations. It's unlikely to be an issue in existing units since any problems would have likely surfaced already. 
• If operating on Liquid Propane (LP), verify fuel levels are above 30%.
• This error may also occur if the generator does not have sufficient fuel supply. See the How Do I Determine the Proper Fuel Pressure for My Air-Cooled Home Standby Generator? article for more information

Note: In extreme weather event circumstances, heavy load on the fuel supply grid may result in a decrease in available fuel to the unit, which may result in an error 1902.

Troubleshooting actions

1. Perform checks above.

 

2. Clear the alarm at the generator's control panel: How Do I Clear an Error or Alarm Code On My Home Standby Generator?

 

3. Attempt to start the unit manually by pressing the blue MANUAL button on the controller. 

 

Note: Never start a generator while under load. See the scenario-based considerations below for troubleshooting in an outage/utility power failure.

Scenario-based considerations

 

Next Steps: When troubleshooting works or fails

Additional resources

• Where can I find a list of error codes for my generator?
• What Error Codes Do I Need to Call a Dealer For?
• Where can I find a user manual or other documentation for my home standby generator?