Onan generator · 2 model lines
Onan generator code 26: Alternator Under Voltage
Onan documentation for 2 model lines lists 26 as “Alternator Under Voltage”.
Check your model first. The same code can mean different things on different models. Find the model number on the appliance's data label, then use the matching row below.
What code 26 means by model
| Model line | What the manufacturer says | Source |
|---|---|---|
| QG 2800i / 2500i LP (HGLAA Spec A-B) | The Cummins Onan QG 2800i/2500i LP HGLAA operator manuals list Code 26 as Alternator Under Voltage. | Cummins Onan RV Generator Manuals Cummins Onan QG 2800i/2500i LP HGLAA Spec A Operator Manual A062Y985 Cummins Onan QG 2800i/2500i LP HGLAA Spec B Operator Manual A075S349 |
| QG 7000i DF (HGLCA Spec A) | The Cummins Onan QG 7000i DF HGLCA operator manual list Code 26 as Alternator Undervoltage. | Cummins Onan RV Generator Manuals Cummins Onan QG 7000i DF HGLCA Spec A Operator Manual A079E225 |
What you can safely check
- Reduce connected loads, especially air conditioners and battery chargers.
- Record whether the fault clears with fewer loads.
Stop and call a technician for
- Internal generator electrical output, inverter, controller, sensors, fuel system, ignition, AC circuit, and engine diagnosis belongs to Cummins service or a qualified generator technician.
Generators can produce carbon monoxide, hot surfaces, fuel hazards, moving-part hazards, and lethal voltage. Shut the generator down and do not open energized compartments unless qualified.
Write this down before you call
- generator model/spec
- hour meter
- fault blink count
- loads running when the shutdown occurred
Other codes on Cummins Onan QG 2800i / 2500i LP inverter generators
Full table: Cummins Onan QG 2800i / 2500i LP inverter generators
- 1 High Engine Temperature
- 4 Over Crank
- 6 Low Oil Level
- 12 Output Over Voltage
- 13 Output Under Voltage
- 14 Output Over Frequency
- 15 Output Under Frequency
- 19 Actuator Circuit Fault
- 25 Alternator Over Voltage
- 27 PMA Sense Lost
- 29 Battery Over Voltage
- 31 Engine Over Speed
- 32 Crank Under Speed
- 34 High Inverter Temperature
- 35 EE Checksum Fault
- 36 Mechanical Fault
- 38 Output Over Load
- 43 RAM Fault
- 45 Crank Position Sense Lost
- 49 Actuator Over Load
- 52 Injector/Lift Pump Circuit Fault
- 53 Oil Temperature Sensor Circuit Fault
- 54 MAT Sensor Circuit Fault
- 56 MAP Sensor Circuit Fault
- 67 IGBT Over Current Fault
- 74 Unprogrammed Board
- 81 Alternator Stator Circuit Fault
- 82 Vent Pressure Sensor Circuit Fault
Other codes on Cummins Onan QG 7000i dual-fuel inverter generators
Full table: Cummins Onan QG 7000i dual-fuel inverter generators
- 1 Engine Temperature Exceeded Limit
- 4 Over Crank
- 6 Low Oil Pressure
- 12 Over Voltage
- 13 Under Voltage
- 14 Over Frequency
- 15 Under Frequency
- 19 Actuator Circuit Fault
- 25 Alternator Overvoltage
- 27 PMA Sense Lost
- 29 High Battery Voltage
- 31 Over Speed
- 34 Inverter temperature Exceeded Limit
- 36 Other Faults
- 38 Over Current (Field Overload)
- 43 ECU Fault
- 45 Speed Sense
- 52 Fuel Injector or IPM Pump Circuit Fault
- 53 Oil Temperature Sensor Circuit Fault
- 54 MAT Sensor
- 57 Over Prime Or LPG Pressure Sensor Fault, The LPG Solenoid Valve Fault
- 73 AC Output Circuit Fault
- 81 Alternator Stator Circuit Fault
- 85 Oxygen Sensor Fault