Onan generator · 3 model lines
Onan generator code 31
Most Onan documentation lists 31 as “Over Speed”. Some model lines word it differently or give it a different meaning: QG 2800i / 2500i LP (HGLAA Spec A-B) (“Engine Over Speed”).
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 31 means by model
| Model line | What the manufacturer says | Source |
|---|---|---|
| HGJAA / HGJAB / HGJAC and HGJBB operator manuals | The Cummins Onan operator manual lists Code 31 as Over Speed. | Cummins Onan RV Generator Manuals Cummins Onan Generator Set for RV Operator Manual A031C171 Cummins Onan Generator Set for RV Operator Manual A035D009 Cummins Onan RV Generator Set HGJAA/HGJAB/HGJAC Spec A-E Operator Manual 983-0101 |
| QG 2800i / 2500i LP (HGLAA Spec A-B) | The Cummins Onan QG 2800i/2500i LP HGLAA operator manuals list Code 31 as Engine Over Speed. | 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 31 as Over Speed. | Cummins Onan RV Generator Manuals Cummins Onan QG 7000i DF HGLCA Spec A Operator Manual A079E225 |
What you can safely check
- Turn the generator off.
- Do not restart repeatedly after an overspeed fault.
- 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 letter
- hour meter
- fault blink count
- loads running when the shutdown occurred
Full code tables for these models
Related troubleshooting guides
Official sources
OnanCummins Onan RV Generator ManualsOnanCummins Onan Generator Set for RV Operator Manual A031C171OnanCummins Onan Generator Set for RV Operator Manual A035D009OnanCummins Onan RV Generator Set HGJAA/HGJAB/HGJAC Spec A-E Operator Manual 983-0101OnanCummins Onan QG 2800i/2500i LP HGLAA Spec A Operator Manual A062Y985OnanCummins Onan QG 2800i/2500i LP HGLAA Spec B Operator Manual A075S349OnanCummins Onan QG 7000i DF HGLCA Spec A Operator Manual A079E225