Common Fault Codes on Generac Generators

Generac Error Code and A&J Logo

Generac was founded in 1959 and was the first to produce home standby generators at affordable prices. They also made the first engine intended specifically for generator use. Generac has a reputation for their wide range of reliable power products including portable, residential, commercial and industrial generators. They have earned their spot as the #1 manufacturer of home backup generators and the top designer and manufacturer of both manual and fully automatic transfer switches and accessories for backup power applications up to 2 MW. The Generac Mobile line offers powerful and high-quality light towers, trailer-mounted mobile generators and combination units that are built for harsh environments and a variety of industries. Following are a few of the common fault codes on Generac generators, along with their dependable solutions explained.

Generac Fault Codes

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RPM Sense Loss, Code 1505/1515

RPM Sense loss is a common fault indicated by the code 1505/1515. If this fault arises, it usually means there are internal issues or a problem with the fuel supply. For code 1505 “the RPM alarm is set when a 2 cylinder unit is cranking” and for code 1515 “the RPM alarm is set when a single cylinder unit is cranking. Both codes are caused when the controller told the engine to crank, but did not get a signal back that the engine was actually turning. Possible causes for both codes are a dead or bad battery, bad starter or wiring to the starter, or ignition coil problems.”  If the unit is 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.  Try putting it back in AUTO and then restart.  If it does not start after doing this, you will need to place a service call. If the unit will not start in AUTO when there is utility loss, clear the alarm by pressing the ENTER button twice, then press AUTO.  Then, using the control panel, check the battery.  To do this, navigate to the BATTERY MENU option from the MAIN MENU.  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.” (source)

Low Oil Pressure, Code 1300

The fault code 1300 indicates low oil or low oil pressure.  “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.  If the oil level is good and your unit is still not working, a service call is needed.”Other possible causes could be the low oil pressure switch being faulty. In this case, the“oil pressure should be checked and the switch replaced. It is also possible that there is an internal problem with the engine not building oil pressure. This would require an oil pressure test to verify.” (source)

High Temperature, Code 1400

High temperature is indicated by fault code 1400. If this fault occurs,“The high engine temperature switch has closed and shut the unit down for exceeding the engine temp high limit. The unit should be checked for debris blocking the vents that might be restricting airflow. If nothing is found, the high temp switch and its wiring should be checked.” (source)

Overcrank, Code 1100

The overcrank fault, represented by the code 1100, essentially “means that the controller is telling the engine to start, but it cannot start for some reason. The controller has verified that the engine is actually cranking, but not starting. This is most likely a fuel or maintenance related issue.” If your home standby is displaying this error code, resetting the controller and restarting your unit may do the trick.  If your unit does not start after two automatic attempts, there is an issue.  Make sure the gas 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.  If the gas is on and your unit is still not working or is running rough, contact an authorized service dealer.” (source)


These are a few of the most common fault codes on Generac Generators. The product manuals provide clear explanations and easily achievable solutions for each. Generac has confidence in their products and offers great product support. The fault detection system on Generac generators is trusted and works to prevent malfunctions and electrical hazards. Generac guarantees quality products with predictable and safe performance. “At Generac, we protect the things that power your life by providing quality, affordable power solutions.”


A&J Generator and Equipment are your Generac standby generator experts! A & J Generator has a very in depth maintenance program made to find problems before outages exploit them. A&J performs 2 maintenance visits a year (every 6 months). A&J’s master Generac technicians know each model in and out. The maintenance program is meant for the homeowner to get the most out of their generator and prolong the life of their investment.

Contact the Generac Experts

If you are experiencing any of these error codes on your Generac whole home generator call A&J Generator today!

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