Sold my car, buyer wants to return it ?? Help ?!?

[Alex3369]

Hi,
So i sold my car last week, a trusty old girl who did me well between 135000 and 164000 at time of sale. The car was test driven and agreed upon and drove away with it being stated that the engine system service light is on and that she needed some work.
The buyer contacted me today saying the gearbox light has come on after a week of driving, what can I do as this never happened to me and I sold the car thinking it was in good running order besides her stated issues???
Thanks,
Alex

[Alex3369]

Just in response, yes it was a private sale.
Thanks for the advice folks I was beginning to get a bit worried.