There is no simple answer: it depends in large part on how the sale occured and whether the same corporate entity still exists. Companies can be sold in two basic ways: either the corporation itself (or the LLC) can be sold, in which case the buyer takes it subject to all contracts, agreements, and obligations; or the assets are sold but not the corporate entity, in which case the buyer only takes those obligations which he, she, or it specifically assumes (or takes on). So it may be the case that the new company has to honor the old company's warranties, but it's not a given; it depends on the circumstances.