I sold a car a few weeks ago. The car had previously had a check engine code, but I took it to the shop to get fixed. Problem solved, until a few days later, light comes back on. I take it back and they do no diagnosis on the car besides pulling the code and give me five possibilities that the problem could be, one being the spark plug, so I said I'd change that and left. There is no receipt for work, nor was I charged for this visit. I changed the plug and never had a hiccup out of the car for a few hundred miles. Problem solved. The car had been for sale for a few weeks prior to this work being done, but a few hundred miles after the repair, I found a potential buyer. He looked at the car in the pitch black dark with a flashlight and it was also raining. I told him the work that had been done on the car and gave him the receipt for that work. I didn't mention the second visit, because to the best of my knowledge the car was fixed. I also told him I do all the work on my cars myself, except the work I had the receipt for. I produced a three week old receipt from having the emissions done as well, and he signed as "AS-IS" contract. He sends me an email the next day saying the car is messed up. He seems like the type who would be lawsuit happy, so I just brushed it off and told him I disclosed everything (to my knowledge, I had, just not about the second visit to the shop bc I deemed it irrelevant). Well, he ends up getting a statement from my mechanic that says I brought the car back and was told five possibilities that the issue could be, but that "no formal diagnosis was done on that visit". Now he is suing me for the ad saying "never any mechanical problems" Yet, I disclosed the receipt for what was minor work the mechanic had done previously, so he knew it had been worked on. And the second count is of knowing the head gasket was blown before I sold it to him, which was never diagnosed or confirmed in any way when I owned it, the mechanic made an assumption about that as well as four other possibilities, none of which were confirmed. I still don't think he has anything on me because the car was running fine when he bought it, the check engine light was not on, and he drove it an hour away without any problems, the issue happened the next day. Thoughts? Oh yeah, he did not take it to a mechanic to get the car checked out either and my mechanic's statement said that I mentioned I would change the spark plug myself after I left his shop, therefore, trying to fix the problem.