Is the seller responsible for the car faults after sale and insurance transfer?

Hello Sir/Madam,

I put an ad in one of the online portals for selling my used vehicle which I brought from a private person 4 months before. When I purchase it, the seller did not disclose to me the faults of the vehicle.

One buyer came to me seeing my advertisement and agreed for 10,750/-. While inspection at ADNOC, they found that the car is having some issues.

He agreed with me that he will take the car with the issues with a very low amount of money 3,300/-. I transferred the insurance, but could not transfer the car in his name due to RTA's short working hours in Ramadan.

Even I did not take any advance from him. Later one mechanical part got damaged. As a seller, I informed him as the buyer. Now he is saying that I have to fix it and sell him at a lower price than agreed.

The repair may cost me around AED 1,200/-. Now I don’t want to sell at this big loss and I told him the same. But he is saying that he will go to govt. authorities.

What should I do?

Please help.