DIAGNOSIS Insufficient rinsing after the descale cycle. Vinegar residue remains in the internal tubing and tank.
FIX You must flush the system. Fill the reservoir with fresh cold water. Run a minimum of 10 full water-only brew cycles (no K-Cup). Use the largest 12oz setting for maximum flow. After 10 cycles, taste the water from the machine. Repeat until no vinegar taste remains.
IF THAT DIDN'T WORK If taste persists, scale may have loosened but not fully flushed, trapping vinegar. Use a commercial descaling solution specifically formulated for coffee makers, which often rinses cleaner than vinegar.
HEADS UP Always perform the rinse cycles immediately after the descale solution finishes. Letting vinegar sit in the hot system for extended periods can intensify the taste and potentially damage seals.