Underspeed: Error Codes 1600-1603

 1. Identify non-essential loads.

• Review the loads connected to the unit.
• Identify loads that are not critical during an outage. 

2. Remove non-essential loads.

• Disconnect or deactivate non-essential loads.

• This can be done by unplugging non-essential loads or switching off non-essential breakers at your main electrical panel. 

• Ensure that the remaining load is within the unit's recommended operating capacity. 

3. Verify load management device functionality.

• Check any Generac Load Managers for functionality and correct configuration for lockouts. 

Note: If the engine speed issues continue without a load, continue with additional troubleshooting checks below or contact a Generac IASD for further diagnosis.

If there is a sudden change in load, it may not be able to maintain the required speed. (i.e., large air conditioning unit powered on).

• • If you utilize any load management systems, verify they work as expected. (Generac Load Manager, Smart AC Module)
    • What Is an Integrated Smart Air Conditioning Module (SACM)?
    • What is a Generac Load Manager (previously known as a Smart Management Module (SMM))?
  • If the generator's speed fluctuates audibly, try running it without a load to determine if something in the house is pulling irregularly or too much power. 
  • Remove non-essential loads
  • If the engine speed issues continue without a load, consider the maintenance steps below or contact a Generac IASD for further diagnosis.

Verify that the fuel shutoff valve is open (ON).

If the valve is closed (OFF) or partially closed, the correct amount of fuel cannot reach the unit and may cause issues. 

For Next Generation Air-Cooled Standby Generators with a Power Zone 200 controller, fuel selection is configured in the Field Pro app during installation.

For Guardian series generators with Evolution controllers, the unit is capable of operating on Natural Gas (NG) or Liquid Propane (LP) and is set manually during installation in two places:

• • • Controller menu setting: The controller should be set to match the fuel source being used. 
      • How do I verify the correct fuel selection is selected for my generator?
    • Fuel jet orientation: The fuel jets must be physically oriented to the correct fuel type.
      • How Do I Perform a Fuel Conversion on My Air-Cooled Home Standby Generator?
    • The controller fuel selection and the fuel jet orientation must match the fuel source used. 
      • Important: If your unit was not recently installed, these settings are unlikely to be incorrect. However, verifying them is still considered best practice to rule out a potentially user-resolvable issue. 

For units operating on Liquid Propane (LP)

• • • When LP levels drop below 30%, fuel pressure may be affected, which can cause operational issues. Check your LP fuel levels to verify you are above 30%. 

For units operating on Natural Gas (NG)

• • • Natural gas grids can be impacted during major outage events or construction. Contact your natural gas supplier to verify any known issues in your area. Most natural gas suppliers post outage or supply disruption alerts on their websites. 

• Improper fuel pressure can lead to operational alarms. However, due to the specialized equipment and safety considerations involved, fuel pressure checks must be performed by a professional. 
• Before considering fuel pressure, it's important to follow a systematic diagnostic process with a Generac IASD. Think of this like checking a low tire—before replacing it, you would first check the air pressure and see if it holds air. Similarly, fuel pressure should only be evaluated after ruling out other common causes like the fuel shutoff valve, fuel levels, and air intake. 
• If all other troubleshooting checks do not resolve the issue, work with your dealer to determine whether contacting your gas supplier to verify fuel pressure is the next logical step in the troubleshooting process.
  

• • Maintain a clear 3-foot area around the unit. 
  • Remove any debris, vegetation, or snow that could block airflow. 

Dirty/blocked air filter

• Inspect the air filters for dirt, damage, or blockage. Air filters can prevent airflow to the engine, affecting the fuel-to-air mixture ratio and engine performance. 
• How Do I Check and Change the Air Filter On My Home Standby Generator?

Cold weather conditions

• In freezing temperatures, moisture in the air filter can freeze, blocking airflow to the engine.
• If temperatures are low, check the air filter for ice buildup and clear any obstructions.
• How to defrost a frozen air filter on a home standby generator 

Sometimes, checking user-serviceable components and performing recommended maintenance can temporarily or permanently resolve engine speed errors. Like any engine, proper maintenance and adherence to the recommended maintenance schedule are essential for reliable operation and unit longevity. Neglecting routine maintenance can lead to performance issues and potential errors. 

• Check the condition of the air filter. Blocked or restricted airflow can affect engine performance: 
• How Do I Check and Change the Air Filter On My Home Standby Generator?
• Verify maintenance items have been completed per the maintenance schedule. 
• Where Can I Find the Maintenance Schedule for My Generac Home Standby Generator?

In an outage scenario, overload conditions and fuel supply issues should be key troubleshooting considerations for underspeed errors:
Overload Conditions during an outage: 

• If the home has bone an extended time without an outage, changes in demand may have occurred since the generator was first installed. Additions like a home expansion, pool heater, or second AC unit can increase the load beyond the generator's capacity, especially if load managers aren't functioning correctly. 

Fuel supply issues during an outage: 

• Liquid Propane (LP): Levels below 35% can affect performance. 
• Natural Gas (NG): grids may be stained or damaged during widespread outages. Check with your NG supplier for outage or grid status updates. 

Important: Anytime power transfer has occurred and the generator is under load, all loads must be disconnected before restarting. The generator must be allowed to reach full speed and "warm up" before reconnecting loads. 

• How do I know if my generator is currently under load?

Guardian series generators with Evolution controllers do not exercise under load, so troubleshooting should not focus on overload conditions or sudden changes in load. 

Next Generation Air-Cooled Standby Generators with Power Zone 200 controllers can exercise under load if they are configured to do so in Mobile Link. This section is only applicable to these units if they are NOT configured to transfer loads during an exercise.

When an underspeed alarm occurs during a generator's exercise cycle, consider the following:

1. Is it a recurring issue?

• If the generator was installed within the past year, the problem is commonly related to the installation. Contact the installer to confirm the installation meets specifications. 
• Underspeed alarms during exercise are typically related to fuel delivery issues or routine maintenance, not electrical problems. The installer responsible for the fuel system should investigate, focusing on fuel pressure and regulator distance.
  • Improper installation can lead to competition for fuel supply between household appliances and the generator and inadequate fuel supply. 
  • Improper regulator placement can impact fuel pressure, resulting in starting issues. 
  • Improper pipe sizing can impact fuel pressure, resulting in starting issues. 

2. Seasonal weather changes:

• Fuel pressure that was barely adequate in summer may cause issues in winter due to colder temperatures.

3. If the generator has been installed for over a year:

• Overspeed alarms are more likely linked to maintenance.
• However, if your home's fuel system has been modified recently, these changes could be contributing factors. 

Troubleshooting Steps

• Start with general troubleshooting as outlined above. 
• If unresolved: 
  • For generators installed within the last year, contact the installer. 
  • For generators older than one year, contact a Generac IASD.

• This may be due to air pockets in the fuel system. When the fuel system is installed, if the air is not correctly bled from the fuel lines, it may contribute to starting issues temporarily due to air pockets in the fuel line. .
• For Next Generation Air-Cooled Standby Generators with Power Zone 200 controllers, fuel selection is done in the Field Pro app during installation.
• For Guardian series generators with Evolution controllers, confirm that the correct fuel was selected during setup at the controller.
  • How do I verify the correct fuel selection is selected for my generator?
• For Guardian series generators with Evolution controllers, units are factory-set to Natural Gas. If you are using LP, you must select LP at the controller and adjust the fuel jet nozzles to the LP position.
• For more information on the field conversation of the fuel jets, see the following article:
  • How Do I Perform a Fuel Conversion on My Air-Cooled Home Standby Generator?
• There may be an issue with your fuel pressure or fuel system. For this type of issue, we recommend contacting your installer to verify the unit has been installed according to the specifications outlined in the installation manual.

Note: A minimum 250-gallon LP tank is required for all home standby generators that utilize LP fuel.

Resolving intermittent underspeed issues can be challenging because they are difficult to replicate. While we recommend contacting a Generac IASD for diagnosis, you can help by noting the conditions when the issue occurs. Consider patterns such as:

• Does it happen during a specific season?

• Is it more common in cold or warm weather?

Providing detailed observations can help identify the root cause, as the ability to replicate the issue is key to an accurate diagnosis.

Additional considerations:

1. If the generator was installed within the past year, the problem is commonly related to the installation. Contact the installer to confirm the installation meets specifications.

• Underspeed alarms are typically related to fuel delivery issues or lack of routine maintenance, not electrical problems.
  • The installer responsible for the fuel system should investigate, focusing on fuel pressure and regulator distance.
    • Improper installation can lead to competition for fuel supply between household appliances and the generator and inadequate fuel supply.
    • Improper regulator placement can impact fuel pressure, resulting in starting issues.
    • Improper pipe sizing can impact fuel pressure, resulting in starting issues.
  • Verify that the routine maintenance schedule has been followed. 
    • Where Can I Find the Maintenance Schedule for My Generac Home Standby Generator?

2. Seasonal weather changes:

• Fuel pressure that was barely adequate in summer may cause issues in winter due to colder temperatures.

3. If the generator has been installed for over a year:

• Underspeed alarms are more likely linked to maintenance.
• However, if your home's fuel system has been modified recently, these changes could be contributing factors.

Troubleshooting Steps

• Start with general troubleshooting as outlined above.

If unresolved:

• For generators installed within the last year, contact the installer.
• For generators older than one year, contact a Generac IASD.

For additional general troubleshooting, see the following article: Troubleshooting intermittent or difficult to replicate alarms, faults, and error codes

• What do I do when I expect a snow storm, or if there is snow building up around the unit? article for more information. 

• If the unit has been installed within the last year, this may point to an issue with the installation that has only become apparent due to seasonal changes. 

• If the unit has been installed for over a year, verify that the routine maintenance and maintenance schedule has been followed according to your owner's manual. 
• Where can I find a user manual or other documentation for my home standby generator?
• Where Can I Find the Maintenance Schedule for My Generac Home Standby Generator?