Hopefully you guys can suggest what happened. I had a local shop do an oil change and a small weld on the exhaust today on my 06 V8 4R. The two flanges connecting two exhaust pipes under the passenger's side floor pan were rusted to the point of separation and were loud.
The mechanic took the pipe off from the flange towards the driver's side and disconnected it at another flange that starts to go up towards the driver's side cat. He had to disconnect the lower O2 sensor during the repair.

After it was back together I drive way and notice the VSC trac, VSC and check engine lights are on. Definitely not on before. Turn around and he says I didn't notice them on then asks were they on before.

He read the code and says it the upper bank on the driver's side which he says he didn't go near. He reconnected the lower O2 sensor and cleaned it but it was still on.

Obviously there was something done by him during this repair to throw this code.

Any ideas?

Thanks