1.   A special radio transceiver called a code grabber, hidden in a nearby car, could intercept and store the signal, code and all.

2.   Later, the code grabber could retransmit the signal and open the locks.

3.   Since the receiver expects no two signals to be identical, code grabbers that play back the same signal are simply ignored.

4.   Theoretically, a code grabber with a computer attached could figure out basic rolling code signals and anticipate the next code in the sequence.