A car key programmer is a device that can be used to recode the transponder in a mechanical key or fob. Some modern automobiles have specially coded transponders in their keys and will not start or drive unless the correct signal is received. In some cases, a new key can be programmed without any special equipment, although many vehicles require a device called a key programmer. A key programmer can be a standalone entity, although sometimes integrated with complex scanning tools. Key programmers typically connect bi-directionally to the On-Board Diagnostic II (OBD-II) port.
When a key is replaced on a modern automobile, the new unit often turns the mechanical switch but fails to initialize the system or start the vehicle. When this occurs it is usually because the transponder in the key has not been coded for that particular system. Keys can often be obtained from either a dealer or a locksmith, although they must be coded regardless of source. Some vehicles allow the owner to code their own key, which usually requires the presence of one of their original keys. This process differs from vehicle to vehicle, although it usually consists of inserting the original key into the ignition, depressing a special combination of brake and accelerator pedals, and then replacing the original key with the new, uncoded one.
When a vehicle does not have a self-programming feature, a key programmer is usually required to do the job. These programmers are typically bi-directional OBD-II tools that connect to the same location as other scan tools. Many vehicle manufacturers sell units that program keys specifically for their vehicles, although generic units that can handle a variety of makes and models can also be found.
The process of using a key programmer typically involves plugging the tool into the OBD-II interface so it can communicate with the vehicle. Each programming tool has different options and procedures, although they usually allow the operator to retrieve the programming data from the computer and then recode the transponder and computer to make them work together. After using the key programmer, the new key should work the same as the old one.
Some vehicles use key fobs instead of traditional lock and tumbler keys. In some cases, the key fob only needs to be in close proximity to the vehicle to work, while other cars require it to be inserted into the dashboard. Key programmers can be used with these fobs in many cases and the process is usually similar to regular keys.
