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Car key programming explained

By the Westminster Locksmith Store team · Updated October 27, 2026

Car keys used to be simple pieces of metal. Most modern keys also carry electronics that must be matched to the car before the engine will start. That matching is called programming.

Illustration of a transponder key and a car dashboard immobilizer light

Common key types

  • Transponder keys: a small chip in the key head sends a code to the car. If the code isn't recognized, the immobilizer stops the engine starting.
  • Remote keys: buttons that lock and unlock the doors by radio signal, sometimes combined with a transponder.
  • Flip keys: a folding blade in a fob, usually with a transponder and remote built in.

When you need programming

  • The key is broken or bent
  • A remote or fob has stopped working
  • You've lost a key or the only key
  • You want a spare
  • The transponder chip is damaged

How it's done

The key blade is cut to fit the locks, then the new chip or remote is introduced to the car using diagnostic equipment, or on some models an on-board procedure. Lost keys can usually be removed from the car's memory at the same time so they won't start it.

Dealer or locksmith?

For many vehicles a mobile locksmith can do the work in your driveway, avoiding a tow. Some models need dealer-only access; we'll tell you if that's the case when you call.

Get a key programmed

Call with the make, model and year, and see our car key replacement and automotive locksmith pages.

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