Are cork defects covered by the warranty?

A note in advance: This answer does not constitute legal advice and does not replace such advice. Nevertheless, the question can be answered unambiguously:

A cork defect - i.e. the musty, musty smell and/or dull, bitter taste of a wine due to a defective cork - constitutes a defect that falls under the warranty obligation. Responsible for this so-called cork taint is the chemical substance trichloroanisole(TCA), which is formed by microorganisms such as moulds. If the cork is contaminated with TCA, the wine sealed with it becomes undrinkable over time.

Since the cork defect, as already mentioned, constitutes a material defect (regulated in Germany in § 434 BGB), the seller (i.e. the winegrower or retailer) is liable under the warranty. The exclusion of a warranty for cork defects in the general terms and conditions (AGB) is legally ineffective and can be warned. Instead, the customer has a right to subsequent performance (delivery of a defect-free wine) or he can withdraw from the contract, reduce the purchase price or demand compensation for his damage or expenses (regulated in Germany in § 437 BGB).

These regulations apply uniformly to stationary trade as well as to online and mail-order trade: Just as with a purchase in a retail shop, an online wine merchant must offer a two-year warranty for new items; for used items (which, however, only applies theoretically to wine), the warranty can be reduced to one year.