Car Keys

Three keys in one

Most car keys are actually three keys in one.

  • A mechanical key to release the steering lock.
  • A coded ‘electronic transponder chip’ read by the car when the key is inserted into the ignition.
  • A remote control to unlock doors and turn off the alarm.

These keys are secure but can be expensive and time-consuming to replace if lost or broken.

For greater convenience, many cars have done away with the mechanical key altogether and offer remote keyless entry and remote keyless ignition.

All you have to do is have the ‘key’ in close proximity in a pocket or bag and the car uses sensors to automatically ‘talk’ to the key.

  • Cars with keyless entry may be more vulnerable to theft.
  • Gangs have been known to follow the owner and use an electronic device to extend the range of the key so an accomplice near the car can use another electronic device to receive the signal and unlock the vehicle.

If you’re concerned that your car may be at risk, you can protect it by keeping your key in a radio frequency blocking (RFID secure) pouch or wallet.

Transponder keys

Electronic, coded ‘transponder’ chips embedded in the plastic body of the key were introduced in 1995.

  • The chip is passive, so it doesn’t need a battery, and the code is read when you turn the key in the ignition.
  • If the transponder chip is broken or missing, the engine won’t start and the immobiliser’s control unit will have to be reprogrammed when you get a new key.

Remote controls

Some use infrared but most remote controls use a radio transmitter to send a coded signal to a receiver on the car.

  • The operating frequency (418Mhz or 433.92Mhz) is close to those used by some communications networks, radio amateurs and other common applications.
  • Interference can sometimes occur, preventing you from unlocking the car.
  • Modern cars are less likely to suffer from radio interference but the problem remains for older cars, particularly those built before 1995.

Car thieves may also exploit this issue by using a jammer – a radio transmitter – to block the signal from your remote control when you try to lock your car. Always check your car’s locked rather than assuming the button worked.

If the remote doesn’t work

  • Check that the battery in the key isn’t flat.
  • If you suspect radio interference, try using the remote control closer to your vehicle.
  • In extreme cases, AA patrols have towed cars away from interference, so the remote can work.
  • Cars with remote central locking should have a bypass system using the normal metal key to unlock the doors without setting the alarm off. This ‘auxiliary entry’ system will be explained in your handbook. Source AA
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