5-8 Error Code on Onan 7KW Gas Generator

[MobileAviator]

My Class A Gasser has an Onan 7KW gasoline powered generator. The rig was purchased new in August 2015, the generator has had regular annual maintenance with semi-regular monthly exercise, and currently has 346.5 hours and is due it's next service.

A couple of months ago, the generator died after running @ 1/2 hour, and the status light on the generator itself showed error code 5-8 indicating excessive exhaust gas temperature. The error code on the dash mounted hour meter shows 8111.5.

Recently, the run time got as low as 5 minutes until shut down, and now will not start at all, immediately showing the 8111.5 error code on the hour meter.

Thinking there might be a wasp nest or other exhaust pipe blockage, I ran a flexible drain cleaning tool up the exhaust pipe, but there was no evidence of blockage.

I've downloaded the Onan Mobile Gen Set Service Manual, Part 1 and Part 2, but the trouble shooting section stops at error code 5-7. Go figure!!

Any ideas or suggestions?

Thanks!!!

[GREGORYJ]

I assume the error code was read counting the 2 sets of the number of
blinks by the start button red light, that is after the first 3 blinks showing a shut down, then pressing the start button once showed 5 blinks followed by 8 blinks for code 58.

[Horsedoc]

Where does one see these codes?

[K_Charles]

Code 81: Exhaust Gas Temperature Sensor Open
Code 58: Exhaust Gas Temperature Shutdown