Problematic buyer

Hello dear community, I sold my car about 3 weeks ago (no accident damage, TÜV until this month, over 240000 km mileage). The buyer was able to test the car and I sold my car to him to the best of my knowledge, without bad intentions. Now he comes after 3 weeks and demands of me that I participate in his repairs, which the TÜV put him up. I did not answer to him until then and he has allegedly already paid his lawyer far I’m a student and so I’m short of cash and the story is making me sleepless nights. Do I have something to fear or can I turn on a lawyer for his threats as a mere attempt to pass his repair costs on to me? Thank you for your answers… Many regards CarDriver1989 PS: Sorry bitt e if this has been posted in the wrong subforum…