How To Fix Generac Error Code 1900

When your Generac generator flashes an “Undervoltage Error Code 1900,” it can be a cause for concern.

This code indicates that your generator has experienced a sudden drop in voltage, which can hinder its ability to provide power when you need it most. 

In this guide, we will explore the causes of Generac Error Code 1900 and provide you with effective solutions to get your generator back up and running smoothly.

Fix Generac Error Code 1900

How To Fix Generac Error Code 1900?

To Fix “Generac error code 1900”, you should check the gas supply, check the oil level, and reset the controller. Additionally, you should also remove some of the loads and check the battery to fix “error code 1900”.

1. Check The Gas Supply

Make sure the gas supply to your generator is turned on. If the handle is lined up with the pipe, your gas is on. If your handle is lined across the pipe, this indicates that the gas is turned off.

  • Check the position of the gas supply handle. If it’s lined up with the pipe, the gas is on. If it’s lined across the pipe, the gas is off.
  • Verify proper fuel pressure, which should be 10-12″ WC at the generator.
  • Inspect the fuel lines and connections for any damage or leaks.
  • Ensure the orange fuel selector knob is set to the correct fuel type.

2. Check The Oil Level

When your home standby is displaying this error, the first thing to check is your oil level. If oil is needed, add oil per recommendations in your owner’s manual. Be careful not to overfill the engine.

To check the oil level in your Generac home standby generator, follow these steps:

  • Ensure the generator is on a level surface.
  • Remove the front panel of the generator housing to access the dipstick.
  • Unscrew the oil filler cap and wipe the dipstick clean.
  • Reinsert the dipstick into the oil reservoir and remove it to examine where the oil level ends.
  • The oil level should be between the minimum and maximum marks on the dipstick.

3. Reset The Controller

If your home standby is displaying this error code, resetting the controller and restarting your unit may do the trick. 

To reset the controller on your Generac generator, follow these steps:

  • Turn the generator control panel to the OFF position.
  • Lift the rubber flap and remove the 7.5 amp fuse from the controller.
  • Disconnect the battery cable and the T1 harness under the controller.
  • Let it sit for 30 seconds.
  • Reconnect the battery cable and the T1 harness.

4. Remove Some Of The Loads

If the unit was running and shuts down, attempting to restart, clear the alarm by pressing the ENTER button twice, then press AUTO. Next, remove some of the loads.

To remove some of the loads from your Generac generator, follow these steps:

  • Turn off all appliances, lights, and items being powered by the generator.
  • If applicable, you can manually turn off circuits in the house’s electrical panel to reduce the load on the generator.
  • After reducing the load, reset any tripped circuit breakers on the generator if needed.

5. Check The Battery Condition

If the battery is in good condition, with proper voltage and passes the load test, it can be left connected and the generator should function properly.

To check the battery on your Generac home standby generator, follow these steps:

  • Completely disconnect the battery, removing the negative battery cable first.
  • Check the battery fluid level and ensure it is well hydrated.
  • Check the battery voltage, which should not be anything less than 12 volts for a 12-volt battery.
  • If the battery needs maintenance, perform the necessary service and ensure the error code is cleared4.
  • Reconnect the battery and ensure it is in good condition for the proper functioning of the generator.

6. Contact An Authorized Service Dealer

If none of the above steps work, contact an authorized service dealer. This error code can be set off when your controller does not detect the correct RPM, or when there is an overload condition.

Contact An Authorized Service Dealer To Fix Generac Error Code 1900

To contact an authorized service dealer for your Generac generator, you can follow these steps:

  • Visit the Generac website at
  • Enter your information to find a service provider closest to you.
  • Alternatively, you can visit the Generac dealer locator at to find sales and service dealers.
  • Select your location and the product or service you are looking for to view retailers, service centers, and dealers in your area.
  • You can also call Generac customer service at 888-GENERAC (888-436-3722) for assistance.
  • If you are experiencing an emergency service issue, contact Generac Customer Support at 1-888-GENERAC (1-888-436-3722) for immediate assistance.