When I sold my truck last year, the only known mechanical flaw it had was that the gas gauge was flakey. It would occasionally work, but most of the time showed lower than empty. I told them about this, and said we made sure to fill it up often, using the trip odometer to keep track of how many miles since the last fillup.
Got a call a couple weeks later from the buyer stating that the fuel pump had died after running it out of gas. Not sure what he was hoping I'd do, but I simply gave him the part number for a replacement fuel pump, and let him know that it took me about 3 hours the last time I replaced it. Didn't hear from him again after that.
A week after that, got a call from Golden PD who had found the vehicle abandoned on the side of the road. I emailed them a copy of the bill of sale with the buyers name, never heard from them again either.

