# Mazda MX-5 "KEY" warning light

**URL:** <https://community.cartalk.com/t/mazda-mx-5-key-warning-light/39616>\
**Category:** Maintenance/Repairs\
**Tags:** keys, mazda, miata\
**Created:** [November 17, 2009, 3:20am UTC](https://community.cartalk.com/t/mazda-mx-5-key-warning-light/39616 "2009-11-17T03:20:54Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![racy10](https://avatars.discourse-cdn.com/v4/letter/r/f1d935/32.png) [@racy10](https://community.cartalk.com/u/racy10)\
**Post date:** [November 17, 2009, 3:20am UTC](https://community.cartalk.com/t/mazda-mx-5-key-warning-light/39616/1 "2009-11-17T03:20:54Z")

</div>

My 2008 Miata with Advanced Keyless Entry stystem shows a “KEY” warning in red letters sometimes. The manual warns that cell phones could cause this or maybe the key card needs a battery. I’ve put in a new battery. I don’t turn on my cell phone. I’ve taken it to my Mazda dealer who has put in a computer module card, twice now. And, I still get the warning occasionally. Anyone know what’s going on?

---

<div class="post-metadata">

**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\
**Post date:** [November 17, 2009, 3:30pm UTC](https://community.cartalk.com/t/mazda-mx-5-key-warning-light/39616/2 "2009-11-17T15:30:11Z")

</div>

It is hard to say what is going on. I would first suspect a RFI problem. If the trouble happens at a cetain location then there may be a transmitter nearby that is causing the trouble.

---

<div class="post-metadata">

**Author:** ![UncleTurbo](https://avatars.discourse-cdn.com/v4/letter/u/e9a140/32.png) [@UncleTurbo](https://community.cartalk.com/u/UncleTurbo)\
**Post date:** [November 17, 2009, 3:39pm UTC](https://community.cartalk.com/t/mazda-mx-5-key-warning-light/39616/3 "2009-11-17T15:39:15Z")

</div>

If you keys for other cars on the same key ring it can confuse the car’s key security system. Try separating all the keys and see if it makes a difference.

---

<div class="post-metadata">

**Author:** ![holden\_magroan](https://avatars.discourse-cdn.com/v4/letter/h/49beb7/32.png) [@holden\_magroan](https://community.cartalk.com/u/holden_magroan)\
**Post date:** [March 30, 2010, 4:41pm UTC](https://community.cartalk.com/t/mazda-mx-5-key-warning-light/39616/4 "2010-03-30T16:41:58Z")

</div>

Sounds to me like your key fob battery is weak , you can purchase one at walmary