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Mazda MX-5 "KEY" warning light

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?

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.

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.

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