Generac codes 1600–1603: underspeed

Record whether it happened during an outage, an exercise cycle, a new installation or cold weather, and which large loads were starting.

Check for overload or a sudden change in load. Generac notes that the startup surge of a large appliance can be 3 to 4 times its running wattage, so several large loads starting together can bog the generator down, and that a sign of overload is audible fluctuation in generator speed. To test, run the generator with no loads connected: if it runs fine, remove non-essential loads by unplugging them or switching off their breakers at the main panel and make sure the remaining load is within the unit's capacity, and check that any Generac Load Manager works and its lockouts are configured. Then check the fuel supply and shutoff valve, the airflow at intake and exhaust, and the scheduled maintenance.

Correct only the proven load, fuel supply, airflow or maintenance condition, then clear the alarm once: on an Evolution controller press OFF, ENTER twice, then AUTO, and on a Power Zone 200 controller hold OFF for 3 seconds. Generac's troubleshooting steps are meant to rule out simple causes, and it says errors that persist or come and go should be handled by a dealer.

Test unloaded, then return loads one at a time. Never start a generator while it is under load.