Pep Boys state inspection rip off Pittsburgh, Pennsylvania

I dropped my car off at Pep Boys, 4571 McKnight Road, 15237? for a state inspection. The car was well taken care of and I didnt expect any issues. An hour later Ricky from Pep Boys called to tell me that the "check engine" light came on and it will cost me $90 to diagnose it. He was extremely rude, tried to educate me on Pennsylvania laws regarding state inspection, and even implied that I lied about the condition of the car when I dropped it off.

I asked Ricky what is the error code and all I got was a sleazy response that "it gives us an idea where to look at" and that I really need to pay for it. I refused to pay for the diagnosis but was still forced to pay ~$30 for the failed inspection. When took the car home and googled the error code I found out that it is a coolant temperature issue, which could have a number of possible causes, none of which seemed worth $90.

Long story short, I checked what I could myself (temperature sensors, thermostat, etc), couldn't find anything wrong with it, cleared the errors triggering the "check engine" light, used the car for about 2 weeks / 500 miles, and took it to another place for the state inspection. It passed the inspection without issues and 2000 miles later the "check engine" light has not come back on.

I can't help but think that Pep Boys mechanics triggered the error code somehow - maybe just by being clueless but possibly deliberately (unplugged the sensor perhaps?). Such attempts to coerce customers into paying for fixing nonexistent problems are disgusting. Even though my financial loss in this interaction was small (the cost of the failed inspection), I will stay away from Pep Boys from now on and will advise anyone I know to do the same.