Exhaust leak=derate

I'd wrap the tape around it. Drive to a shop or truckstop. Anything not to use that road service guy.
(1) He should have showed up without a new flex pipe.
(2) He had to go back to his shop and examine it, to determine he couldn't weld it?
Ya I'd have more faith in a freshman year diesel vot student.

 

You will have to tell us the truck make, model, year and engine before can help you.

 

The integrity of the exhaust system is critical to the Emissions system.
Yes, after you repair the hole. Do the parked regen, that should clear the code. And you'll be good to go.
The yellow light may still be on for a day or so, but as long as the hole is fixed and it was able to do a successful regen it will clear the code in short order.

 

If he unhooked the battery cables for awhile would that help reset things? No?

 

Your probably right, it can't be that easy.

@pushbroom can you help out?

 

I dont recall any specific codes that come up on the dash indicating there is an exhaust leak. Did the mobile tech at least have a laptop to verify what code it is?
The exhaust after turbo pipe is common to leak. There is probably something else wrong as well that needs to be repaired. It needs to get on a scanner/laptop. Most of things are a waste of time.