Universal diagnostic library
Generator and outdoor-power diagnostics
Generator and outdoor-power diagnostics: carry the controller code, fuel, outage and load context through every step.
Three problems account for most standby generator calls: it starts but the house gets no power, it will not start when the grid goes out, and it starts and then shuts down. They have different causes. If the generator runs but the house stays dark, the fault is usually between the generator and the house: the main breaker on the unit, the transfer switch or a tripped breaker in the panel. If it will not start during an outage, the usual causes are a flat battery, a closed gas valve or a controller left in Off. If it starts and quits, read the alarm code first, because shutdowns for low oil pressure, high temperature or low speed are protective and repeat until the cause is fixed.
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12 complete records in this directoryGenerator runs but the house does not receive backup power
A running engine does not prove the transfer switch moved or generator output is available. Keep hands out of transfer equipment.
Open record Standby generators · no startHome standby generator will not start during an outage
Do not keep clearing alarms. Record the controller, confirm AUTO, verify fuel availability and remove household load before one controlled restart.
Open record Standby generators · shutdownStandby generator starts and then shuts down
The alarm and exact shutdown moment matter. Speed, temperature, oil pressure, fuel and overload protections cannot be diagnosed by repeated loaded restarts.
Open record Generac standby generator · exact alarm familyGenerac codes 1500–1522: RPM sensor loss
Codes 1500 to 1522 are the RPM SENSOR LOSS alarm, shown with a red LED. Generac says the controller does not detect a valid RPM signal during startup, or lost a valid signal while running. End-user troubleshooting is the same for every code in the range, and the likely causes differ by whether the unit failed to start or shut down while running.
Open record Generac standby generator · exact alarm familyGenerac codes 1600–1603: underspeed
Codes 1600 to 1603 are the UNDERSPEED alarm, shown with a red LED: engine speed (RPM) is too slow. Generac says the cause is that the unit is overloaded or has fuel supply issues, and the Mobile Link message says an underspeed alarm occurred.
Open record Generac standby generator · exact alarmGenerac generator code 1100 or 1101: overcrank
Codes 1100 and 1101 are the OVERCRANK alarm, shown with a red LED: the unit turns over but will not start, and after the engine has tried to crank 5 times without starting the controller triggers the alarm. Generac lists these common causes: inadequate fuel pressure, the fuel shutoff valve being OFF, improper fuel selection in the controller (Evolution) or in the Field Pro app (Power Zone 200), an air filter problem, improper installation and a low battery.
Open record Generac standby generator · exact alarmGenerac generator code 1300: low oil pressure
Code 1300 is LOW OIL PRESSURE, shown with a red LED: the low oil pressure sensor triggered a shutdown because of inadequate oil. Generac says the cause is typically low oil from oil consumption, leaks or a lack of maintenance, and that your options are limited beyond basic checks and one attempt to clear the alarm and restart.
Open record Generac standby generator · exact alarmGenerac generator code 1400 or 1401: high temperature
Codes 1400 and 1401 are the HIGH TEMPERATURE alarm: the generator is overheated. Generac says the cause is obstructed intake and exhaust ventilation around the unit or inadequate fuel pressure, and asks you to make sure there are no enclosures around the generator.
Open record Generac standby generator · exact alarmGenerac generator code 2400: fuse problem
Code 2400 means the controller’s 7.5-amp fuse is missing, open or not seated on supported Generac platforms. Isolate utility, generator and battery power exactly as Generac directs before inspection.
Open record Generac standby generator · exact alarmGenerac generator code 2800: auxiliary shutdown
Code 2800 or 2801 means the generator was shut down with the Emergency Stop button or, more commonly, an Auxiliary Shutdown switch, shown as STOPPED - ALARM or SHUTDOWN SWITCH with a flashing red LED. Generac says these switches have been required by NFPA fire safety rules since 2017 and sit in accessible places on air-cooled home standby generators. They can be tripped by brushing against one, during maintenance when it was not reset, or even by animals such as squirrels, and a service provider may trip one on purpose so a unit awaiting service cannot run.
Open record Generac home standby generator · exact codeGenerac home standby generator code 2100 to 2103: meaning and exact next steps
2100 to 2103 means Overload, remove load. The generator is being overloaded by excessive electrical load demand, meaning the load exceeds its rated power capacity. The LED is red and the Mobile Link message says an overload alarm occurred.
Open record Generac home standby generator · exact codeGenerac home standby generator code 2202 or 3217 (low fuel pressure): meaning and exact next steps
2202 or 3217 (low fuel pressure) means Low fuel pressure. Generac's Mobile Link card reads "A warning has occurred, ECODE 2202: Low fuel pressure," and its message list gives the warning as code 3217. Fuel pressure alerts show in Mobile Link only if the generator has a Power Zone 200 controller and is registered to a Mobile Link account.
Open recordStandby generators and outdoor power: where to begin
Never run a portable or standby generator indoors or in a garage, and keep it well away from windows and doors because of carbon monoxide. Work on the fuel system or the transfer switch is for a licensed technician. Alarm codes for Generac units are explained one group at a time on their own pages.
Why does my generator run but the house has no power?
The fault is usually downstream of the engine: the unit's main breaker, the transfer switch or a tripped breaker in the house panel.
Is it safe to run a generator in a garage with the door open?
No. Carbon monoxide builds up quickly even with the door open, so run it outdoors and away from openings.