What is the difference between aftermarket remotes and factory remotes?
Factory remotes work on factory systems, which are the original systems that are installed in the vehicle when it is built at the factory.
Aftermarket remotes work on aftermarket systems. Aftermarket systems get put in a car after the car is no longer brand new. Alarm shops, Best Buy, and dealerships typically are the ones that install aftermarket systems in cars. There are many different aftermarket brands that are common. The most popular are ones made by DEI. DEI's most popular brand name is Viper. Most people have heard of Viper because of the commercials they had in the late 1990s (the car would yell "this car is protected by Viper - stand back!")
Factory remotes and aftermarket remotes are almost never compatible with each other.
Aftermarket remotes is a confusing term because lots of people think of it in this way: "aftermarket replacement for a factory remote." For this reason, to avoid confusion, we call an "aftermarket replacement for a factory remote" a "generic factory remote" as opposed to a "genuine factory remote."