- Type of key: blade, remote-head or proximity
- A basic transponder blade, a remote-head key with buttons, and a push-button proximity key each involve a different amount of pairing beyond the immobilizer chip itself, which affects both the parts involved and the time the visit takes.
- How the vehicle's key list is reached
- Some vehicles allow direct access through the onboard diagnostic port, while others gate that list behind a manufacturer-level security session that takes additional steps to establish. Which situation applies to a given vehicle affects how the visit is scoped.
- Vehicle make, model and year
- The chip family, the immobilizer generation, and how reachable the vehicle's key list is all follow from the exact vehicle, so identifying it precisely early on shapes both the blank needed and how much of the visit is straightforward programming versus a more involved security session.