Electrical
Why the code lists online disagree
Search a Generac code and you will get a dozen tables that do not match. One lists 1100 as overvoltage and 1200 as undervoltage. Another lists 1505 as low oil pressure. A third has 1902 as a governor actuator fault. They cannot all be right, and they are copied from each other rather than from Generac.
Two things cause this. Generac has shipped several controller generations, and the code sets are not the same across them. And the lists are transcriptions of transcriptions. We had this wrong on this page too, which is why it has been rewritten against Generac’s own support documentation.
What Generac publishes for the Guardian series
For Guardian air-cooled units from 2017 onward, these are the code families Generac lists.
| Code | What it means |
|---|---|
| 1100 - 1101 | Overcrank. The engine turned over and did not start. |
| 1200 - 1207 | Overspeed. |
| 1300 | Low oil pressure. |
| 1400 | High temperature. |
| 1500 - 1521 | RPM sensor fault. The controller could not confirm the engine was turning. |
| 1600, 1603 | Underspeed. |
| 1800 | Overvoltage. |
| 1900 - 1906 | Undervoltage. |
| 2098 - 2099 | Wiring fault. |
| 2100 - 2103 | Overload. |
| 2299 | Undervoltage overload. |
| 2399 | Stepper overcurrent. |
| Model identification problem | The harness resistor that tells the controller which unit it is attached to. |
From Generac support, "What error codes do I need to call a dealer for". Next Generation series units publish a different and much larger code set.
Generac publishes the full list, including the Next Generation series codes, here: Generac, which error codes need a dealer.
The codes you can act on yourself
Most of the list is dealer work, and Generac says so. These are the exceptions it calls out.
- Battery alarm 2751: inspect or replace the battery first, and only call if that does not resolve it. A standby generator sits for months doing nothing, so the battery is the single most common failure point on the whole machine.
- Battery and charger alarms 2750, 2760, 2770 and 2780: replace the battery, or call.
- Engine oil level 5415 to 5417: check the oil and add or drain to the mark. Call only if the alarm comes back.
- Overload cooldown 7000: call only if the condition persists. A one-off during a heavy load is the system doing its job.
Clearing an alarm, and the trap in doing it
The reset is not the same on every unit, which is one more reason the generic advice online goes wrong.
| Controller family | Procedure |
|---|---|
| Guardian series | Press the red OFF button, then press ENTER. |
| Next Generation series | Press and hold the OFF button for three seconds. |
From Generac support. After clearing, press MANUAL to attempt a start. If the code returns, Generac states dealer service is required.
What actually fails on these, in our experience
Across our service area the pattern is consistent and it is not exotic. Batteries that have sat through a New England winter. Fuel supply, particularly propane tanks sized for a range rather than for a generator under load. Rodents in the enclosure over winter. And units that have not had a scheduled service, so the oil is old and the plugs are due.
Getting it serviced
We service and install standby generators, and the electrical and gas sides are handled by the same licensed team, which matters because the transfer switch and the fuel line are where most of the real problems live. Start with generator maintenance, or generator installation if the unit is past the point of economic repair.
In an extended outage the thing that fails after the generator is the heating system it is powering. If yours has been on the edge, furnace repair is the other call worth making before winter. We cover Manchester, Dover, Sparta and Brick Township.