Service engine soon light???

Ok. So about 2 months ago I got a new motor put in my truck. It was just a stock replacement motor, nothing big. 4.3L v6. They did a long block, and they had to put a new attachment in my exhaust pipe for my o2 sensor because someone put a straight pipe in and cut the cat off. But anyways. Ever sinces I've had the new motor when I go on trips up north or even when I'm driving for an hour or more the service engine soon light comes on. The first couple times I pulled over, checked all the gauges, crawled under my truck, everything. But I couldn't find anything wrong. So when I got home I had a buddy that works at Autozone hook up a scanner and see if my codes were stored. He hooked it up and the scanner just said. Link error. So I don't know if there is something they would have unplugged when they put the new motor in, and didn't plug back in. But is there any reason the scanner tool wouldn't connect to my truck? Also my buddy says on the newer OBD2 systems that it does not store the codes. Is this true? If so that means I would have to rent the scanner for $300 and plug it in when the light comes on. BUT. The scanner isn't connecting. I'm so fucking pissed. I paid almost $5,000 and now I have a trouble light coming on. That's BULLSHIT. Ok. thanks for any help.

take back to the person who did the work tell them to fix. it should be covered under a warrenty

OBD2 systems do store codes even when the service engine light goes off. It's known as a code history. The Scantron Code readers will work.

I would say there is sometype of wiring issue between the OBD2 connector and the ECM if your getting a Link Error. The other cause could be a bad ECM. When the service engine light comes on, you may not find something physically wrong. The way you described the new fitting for the O2 sensor...there could be something wrong there.

Ya. I have this coming tuesday off and I'm taking my truck in. It is so fucked up. I have been smelling coolant for about 2 weeks, I figured maybe some spilled out or something, but the other day it was running hot so I check and it was almost a gallon low. So I'm taking it there and telling them to keep it until it's fixed. So far its leaking coolant, Hard starting, OBD2 port doesn't work, and now the trans is slipping BAD. I'm gonna try and say they fucked that up too. Not sure if they will fix that or not. But it's better than paying $2000 to get the trans rebuilt.