# 2013 Hyundai Sonata - Question About Transponder/Ignition

**URL:** <https://community.cartalk.com/t/2013-hyundai-sonata-question-about-transponder-ignition/146165>\
**Category:** Maintenance/Repairs\
**Created:** [August 6, 2019, 10:52pm UTC](https://community.cartalk.com/t/2013-hyundai-sonata-question-about-transponder-ignition/146165 "2019-08-06T22:52:10Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Gary08](https://avatars.discourse-cdn.com/v4/letter/g/e79b87/32.png) [@Gary08](https://community.cartalk.com/u/Gary08)\
**Post date:** [August 6, 2019, 10:52pm UTC](https://community.cartalk.com/t/2013-hyundai-sonata-question-about-transponder-ignition/146165/1 "2019-08-06T22:52:10Z")

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If my key fob battery dies, I can insert it into a designed slot that is located under my armrest to start my car. My question is how is it sending a signal to the ignition to start? My key fob is 100 plastic with no metal contacts anywhere on its surface. So when I plug fob into designed plastic slot (under armrest) no electrical contact is made. How does it send signal?

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**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\
**Post date:** [August 7, 2019, 12:11am UTC](https://community.cartalk.com/t/2013-hyundai-sonata-question-about-transponder-ignition/146165/2 "2019-08-07T00:11:28Z")

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There is a transponder antenna coil in the console slot that sends/receives a radio signal from the key. It works the same as a bladed key that has the transponder in the key handle.

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**Author:** ![It\_s-Me](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/it_s-me/32/12660_2.png) [@It\_s-Me](https://community.cartalk.com/u/It_s-Me)\
**Post date:** [August 7, 2019, 12:20am UTC](https://community.cartalk.com/t/2013-hyundai-sonata-question-about-transponder-ignition/146165/3 "2019-08-07T00:20:37Z")

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> [@Nevada\_545](#):
>
> It works the same as a bladed key that has the transponder in the key handle.

Or the microchip in your dog that can be read when close enough to the scanner.

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**Author:** ![Gary08](https://avatars.discourse-cdn.com/v4/letter/g/e79b87/32.png) [@Gary08](https://community.cartalk.com/u/Gary08)\
**Post date:** [August 7, 2019, 12:35am UTC](https://community.cartalk.com/t/2013-hyundai-sonata-question-about-transponder-ignition/146165/4 "2019-08-07T00:35:31Z")

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So the transponder antenna coil in the console slot send a signal the the removable key in my plastic fob?

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**Author:** ![lion9car](https://avatars.discourse-cdn.com/v4/letter/l/59ef9b/32.png) [@lion9car](https://community.cartalk.com/u/lion9car)\
**Post date:** [August 7, 2019, 12:23pm UTC](https://community.cartalk.com/t/2013-hyundai-sonata-question-about-transponder-ignition/146165/5 "2019-08-07T12:23:08Z")

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I don’t know for sure, but I assume it’s more or less this technology:

> **[Proximity card | Passive cards](https://en.wikipedia.org/wiki/Proximity_card#Passive_cards)**
>
> Passive 125 kHz cards, the more widely used type which were described above, are powered by radio frequency signals from the reader device and so have a limited range and must be held close to the reader unit. They are used as keycards for access control doors in office buildings. A version with more memory, contactless smartcards, are used for other applications: library cards, contactless payment systems, and public transit fare cards.