What "machine" ? And why ?
Have the auto parts place pull the codes for free. Get the code number(not a description).
If it's code P0128, then you'll need to replace the thermostat again but with the correct AC Delco one mentioned before.

There is no need to go to a dealer if it's a simple, do it yourself type repair. Unless you like to give the dealer lots of unnecessary money.

 

I think Dad tends to believe the dropouts at GM shops more than internet "experts". They have all those impressive certificates on the wall, we got nothing but real life experience.

 

I took my car to the shop up the street because I live two hours from my dad. It took about 15 minutes for the guy to fix it. It was a lose wire. It cost a total of $35.00 to fix it.
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Probably that darn ground wire that GM attached to the air filter housing mounting bolt. I moved it to a similar location so it does not happen again. Lol