https://www.vice.com/en/article/z34xnw/hackers-say-they-can-unlock-and-start-honda-cars-remotely
The Honda models that Kevin2600 and his colleagues tested the attack on use a so-called rolling code mechanism, which means that—in theory—every time the car owner uses the keyfob, it sends a different code to open it. This should make it impossible to capture the code and use it again. But the researchers found that there is a flaw that allows them to roll back the codes and reuse old codes to open the car, Kevin2600 said.