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For decades, Generac has produced some of the best generators on the market. Founded in 1959, Generac was the first to engineer affordable home standby generators. 80 years later, Generac is still the #1 manufacturer of home backup generators. Innovation is at the forefront of this company. Still, even Generac’s high-quality generators are prone to the occasional error. Luckily, these errors often have dependable solutions that you can employ to get your generator back in working condition. Depending on the error code, there are steps you can take to troubleshoot the issue. These steps can usually be found in the generator’s manual as calling a professional is usually the last resort. In this article, we’ve listed some common errors you may encounter along with some tips on how to resolve the issue.

Overcrank (Code 1100)

Generac Error Code
This is a common error to see displayed on your Generac home standby. Essentially what this means is that the controller is telling the engine to start, but it cannot. The controller has verified that the engine is cranking but not starting. To resolve this issue, you’ll need to reset the controller and restart your unit. If your unit does not start after two automatic attempts, there may be a deeper issue. Make sure the gas to your generator is turned on. You can tell if your gas is turned on if the handle is lined up with the pipe. If your handle is lined across the pipe, the gas is turned off. If the gas is on and your unit is still not working, you’ll need to contact an authorized service dealer.

Overspeed (Code 1201 / 1205)

Generac Error Code - Overspeed (Code 1201 1205)
This code is usually displayed when the controller detects high RPM. This means that for 3 or so seconds, the frequency (engine speed) was 72Hz or above on an 60Hz unit or 60Hz or above on a 50Hz model. This can be the result of defective ignition coils, and for this, you need to contact an authorized service dealer.


Underspeed (Code 1600)

Generac Error Code - Underspeed (Code 1600)
This code is set off when the controller does not detect the correct RPM. It’s triggered when the engine speed is slowed to 55Hz for a 60Hz unit for 30 seconds (or 40Hz for a 50Hz unit). This could be fuel related or a stepper motor throttle control problem. If your unit is displaying this code, you will need to contact an authorized dealer.

Low Oil Pressure (Code 1300)

Generac Error Code - Low Oil Pressure (Code 1300)
When you see this error, the first thing you should do is check your oil level. This error could be the result of a low oil level and if that’s the case, it needs to be filled.  If oil is needed, add oil per the recommendation found in your owner’s manual. Be careful not to overfill the engine. If the oil level is good, the error may be the result of a faulty low oil pressure (LOP) switch. The oil pressure should be checked, and the switch replaced. Another possible cause of this error is some internal problem with the engine not building oil pressure. This would require an oil pressure test to verify. If your unit still won’t work, a service call is needed.

RPM Sense Loss (Code 1501 / 1505 / 1511 / 1515)

Generac Error Code - RPM Sense Loss (Code 1501 1505 1511 1515)
These error codes will show up if there’s an issue with the cylinder unit. It could have been running and then stalled or lost the RPM signal from the ignition coils. Or the cylinder unit is cranking. Possible causes could be a fuel issue, the LP tank is empty, both ignition coils are damaged, or the unit was overloaded quick enough that the engine stalled and set the alarm. But if the unit is running and suddenly shuts down, you should try to restart it. You can clear the alarm by pressing the ENTER button twice, then press AUTO. Next, remove some of the loads. Try putting it back in AUTO, and then restart it. If the generator still does not run after this, you will need to place a service all. If the generator will not start in AUTO when there is utility loss, clear the alarm by pressing ENTER twice, then press AUTO. Then, using the control panel, check the battery. To do this, go to the MAIN MENU and navigate to the BATTERY MENU option. If it states ‘check battery’, try replacing the battery.  If it states that your battery is ‘good’ when being checked, contact an authorized service dealer.

Overvoltage (1800)

Generac Error Code - Overvoltage (1800)
This error occurs when the unit’s rated voltage output is exceeded for a prolonged period.

A voltage test should be done to determine the problem. Most likely a bad AVR (automatic voltage regulator) which is internal to the Evolution control board.

Undervoltage (Code 1900)

Generac Error Code - Undervoltage (Code 1900)
A sudden drop in voltage can set off this error code. When the output voltage is below 80% of the unit’s rated output for 10 or more seconds, you’ll see this error. All engine functions should be checked as well as voltage. For this code, you’ll most likely need to make  a service call.

Overload (Code 2100)

Generac Error Code - Overload (Code 2100)
The unit will display this code when your controller senses an overload condition. The first thing you need to do is remove the load. Load shedding should be installed to prevent this from happening again in the future. If you remove the load and the problem persists, a service call is needed.

Low Battery

Kohler Generator Error LB
Check the VDC on the battery as well as the controller to make sure they are the same. If the voltage is less than 12.5 VDC, recharge the battery. If the voltage is over 12.5 VDC, check the charge circuit for operation.


There are a variety of error codes that may be displayed on your Generac generator. Although this may not be something you encounter often, you should have a sense of how to resolve the issue. However, if these errors are frequent, there may be a larger issue at play. Most codes will be something you can handle on your own but there may be instances where you’ll need to reach out to a professional generator team. But it is our hope that the information found here in the blog can help you navigate certain situations as they arise.

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