Need help Onan quiet diesel 7.5 code 15

[Captain154]

Need help. The generator starts up fine but dies after just a few seconds. I have tried shutting off all appliances and I have also tried shutting main breaker off at the generator with the same outcome. Has anyone ever had this issue before?

[Sky_Boss]

From my manual...Verify you have the same model...see attached

INVERTER UNDERFREQUENCY FAULT—CODE NO. 15
(Controller not able to regulate to rated frequency)
Corrective Action:
1. Reduce the number of connected appliances, especially when air conditioners and battery chargers
are running.
2. Have air conditioners and other appliances checked for proper operation. (A locked compressor rotor
can cause very low power factor.)