Generator battery
First part to test and price for overcrank, low-battery, and failed exercise faults.
$60-$180
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Generator Fault Codes
Generator fault codes are easiest to solve when you split them by controller and symptom. A Generac Evolution shutdown, a Kohler Decision-Maker alarm, a Cummins PowerCommand code, an Onan blink code, and a portable-generator LED pattern can all describe the same basic failure: the engine did not start, oil pressure is unsafe, speed is wrong, voltage is out of range, or the transfer system did not behave as expected.
Use this page as the generic generator fault-code starting point, then jump to the brand guide once you know the controller.
Start With the Brand Guide
| Generator type | Best guide | Common first checks |
|---|---|---|
| Generac Guardian, EcoGen, Protector, Nexus, Evolution | Generac generator fault codes | 1200 overcrank, 1900 RPM sense loss, low battery, field boost, transfer switch |
| Kohler residential or commercial standby | Kohler generator fault codes | Fail to Start, Low Battery, AVR voltage faults, ground fault |
| Cummins PowerCommand commercial units | Cummins generator error codes | 111 low oil, 115 overcrank, 145 overspeed, 214 overvoltage |
| Cummins Onan RV or marine units | Cummins Onan generator fault codes | 2, 3, 4, and 5 blink faults, carburetor, oil, AVR |
| Honda EU, EB, EM, or EP units | Honda generator error codes | Oil alert, overload light, no AC output, inverter protection |
| Champion portable or standby units | Champion generator error codes | CO Shield, overload, low oil, E01-E08 standby faults |
| Westinghouse iGen, WGen, or PTS units | Westinghouse generator error codes | Overload, low oil, no AC output, inverter fault |
| Briggs & Stratton standby or portable units | Briggs & Stratton generator error codes | FC1-FC12, low oil, overcrank, AVR, low battery |
| DuroMax XP or RS portable units | DuroMax generator error codes | Overload, low oil, CO alert, no AC output |
Common Generator Fault Families
| Fault family | What it usually means | Safe first check |
|---|---|---|
| Overcrank or fail to start | The engine cranked but did not reach run speed | Battery voltage during crank, fuel valve, fuel level, spark or glow-plug basics |
| Low oil pressure | The controller saw unsafe oil pressure or an open sender circuit | Oil level and oil condition before testing the sender |
| High temperature | Coolant, oil, or air-cooled engine temperature is too high | Cooling airflow, radiator screen, coolant level, fan belt, load |
| Overspeed or underspeed | Engine RPM moved outside the safe window | Connected load, fuel pressure, governor linkage, speed sensor wiring |
| Low battery or charger fault | Standby battery is weak or not charging | Battery age, terminals, charger output, utility power to charger |
| AVR or voltage fault | Output voltage is missing, high, low, or unstable | Breaker status, load, brush/slip-ring condition, AVR input and output |
| Transfer-switch fault | Generator runs but load does not transfer | Utility sensing, ATS fuses, control wiring, contactor status |
Quick Diagnosis Order
- Write down the exact code, blink count, or LED color before clearing it.
- Confirm the controller family and model number.
- Check battery voltage at rest and during crank.
- Confirm fuel supply, oil level, and cooling airflow.
- Remove large loads before retesting a voltage or overload fault.
- Use the brand-specific guide for model-specific reset steps and parts.
Buying Parts Without Guessing
Generator parts are model-specific. Match the exact generator model, serial number, controller generation, voltage, phase, and symptom before ordering. A battery, oil pressure switch, AVR, speed sensor, carburetor, or charger board can be the right category and still be the wrong part for your unit.
For standby generators, avoid guessing on transfer-switch wiring, ground faults, overcurrent faults, and voltage-regulator adjustment. Those checks can involve live 240V output, automatic starting, utility power, and connected building loads.