Generac Generator Error Codes: Complete Alarm Code Reference

Quick Answer

Generac standby generators display numeric alarm codes on the Evolution or Nexus controller. The most common codes are 1505 (low oil pressure), 2800 (overcrank - engine failed to start), 1100 (RPM sense loss), and 1902 (governor actuator fault).

When a Generac throws a code, the first thing I want to know is whether it happened during the weekly exercise cycle or during an actual outage. Those are very different problems. Most of what I find in the field is deferred maintenance catching up with people: dead battery, low oil, gummed-up carburetor from sitting too long. Ignore the alarm long enough and you'll have no generator when a real storm hits.

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About These Generac Generator Error Codes

These codes protect the engine from killing itself. Before you start ordering parts, check two things first: the 12V battery voltage and the oil level. A battery below 12.4V will throw phantom codes all day that have nothing to do with the actual engine. I've cleared four active faults on a single unit just by swapping in a fresh battery. This stuff is common, it's fixable, and you don't always need a service call to sort it out.

Most Common Error Codes

Low oil pressure from oil level or sensor40%

Overcrank from fuel delivery issue24%

RPM sensor failure14%

Battery voltage low12%

Governor actuator fault10%

Symptoms You May Notice

The controller display shows a numeric code with the red alarm light solid on, and the unit won't crank even though there's an active power outage outside.
Generator fires up during the Tuesday morning exercise cycle, runs for 20 to 30 seconds, then shuts itself down hard with a fault code.
You hear the starter cranking over and over but the engine never catches, especially in cold weather or when the LP tank is sitting below 20%.
Unit starts, comes up to speed, runs fine for a minute or two, then dies. That pattern usually means a governor or fuel pressure problem, not a one-time glitch.
The Mobile Link app sends you a notification at 2 AM saying the weekly exercise failed and the unit is in alarm.

Tools Required for Diagnosis

Phillips #2 screwdriverFlathead screwdriver (for terminal blocks)Multimeter (DC voltage and resistance modes)10mm socket and ratchet (for battery terminals)Flashlight or headlampClean shop ragLatex or nitrile gloves

How to Identify Your Error Code

ComponentComponent Under Test

Expected Range12.4–13.2 V

ConditionIf Open (OL) or infinite, replace component.

Frequently Asked Questions

How do I read the fault log on my Generac?

On the newer Evolution controller, press OFF and then hit ENTER twice. You'll see the last 10 fault events with timestamps. On older Nexus models, hold ENTER and ESCAPE together for a few seconds. That log is the first thing I check on any service call because it shows me if the generator has been struggling for weeks before it finally gave up. Three overcrank codes on three consecutive Tuesdays tells me a completely different story than one random code with no history behind it. Always read the full log, not just the current code.

Can I reset Generac alarms myself?

Yeah, most of them. Hit OFF then ENTER. But here's the thing about codes like 1505 (Low Oil Pressure) or 1902 (Governor Actuator): those exist specifically to stop the engine before it destroys itself. If you reset the code and the engine sounds rough, knocks, or the code comes right back, stop. Don't keep trying to force a start. One more run with a real oil pressure problem and you're looking at a seized engine, which is a $2,000+ repair instead of a $15 oil fill. Reset it once, watch it. If it comes back, it's trying to tell you something real.

What does the red light on my Generac controller mean?

Solid red means the generator has locked itself out and won't start until you fix the problem. It won't run during an outage, period. A yellow light means scheduled maintenance is due, like an oil change or battery swap. Ignoring yellow is exactly how you end up with red. I get calls every summer from people who've had the yellow light on since February and finally noticed it when the power went out and nothing happened. Don't be that person.

What is Generac error code 2800?

That's the overcrank fault. It means the engine tried to start, cranked for the full allowed time (about 30 seconds), and never fired. On LP units I check the tank level first, then the carburetor for gummed-up fuel. On natural gas I verify the gas pressure is between 5 and 14 inches water column at the unit. About 7 out of 10 overcrank faults I see are fuel-related. The other 3 are either a spark plug that's fouled out or a battery that's too weak to crank the engine fast enough to get ignition. Start with fuel and battery before you go deeper.

How often should I service my Generac to avoid fault codes?

Once a year minimum, even if the hour meter is low. If your generator only runs a 20-minute exercise cycle each week, that's about 17 hours a year. You're basically servicing by the calendar, not the hours. The stuff that prevents most fault codes is simple: fresh oil, a battery you've actually tested with a multimeter (not just looked at), a clean air filter, and confirmed fuel supply. I've seen generators go 10 years without a single fault code because the owner does a proper annual service. And I've seen 3-year-old units already on their second control board because nobody touched them.

Why does my Generac keep throwing different fault codes every time?

Multiple random codes that keep changing are almost always a weak 12V battery. The logic board needs stable voltage to function correctly, and when it drops below about 11.8V you get all kinds of weird, misleading faults. Test the battery with a multimeter before you do anything else. If it's reading under 12.4V, replace it. I'd guess 40% of the 'mysterious' fault code calls I go on get fixed with a $50 battery. It's the most common thing people overlook because the battery just sits in there and nobody thinks to check it.

Related Generac Generator Error Codes

Code: 2800Generac 2800: Overcrank Code: 1505Generac 1505: Low Oil Pressure Code: 1100Generac 1100: RPM Sense Loss Code: 1902Generac 1902: Governor Fault

Models Known to Experience HUB Errors

This repair applies to most Generac generators with this error code. Common model numbers include:

Guardian 7043 (22kW), Guardian 7035 (16kW), Guardian 7037 (20kW), Guardian 7039 (22kW), EcoGen 7291 (15kW), Protector RG020 (20kW), CorePower 6438 (7kW), Guardian 0059153 (24kW)

Written by

Sarah Kim

Smart Home & Specialty Appliance Tech · 12 years experience

Last verified for technical accuracy on March 15, 2026