Issue with remote key fob (ND RF)

Technical Area Electrics & ICE
#1
  1. My model of MX-5 is: ND RF 2017 model
  2. I’m based near: London
  3. I’m looking for technical help or recommendations on an issue with my key fob.

Recently had 3rd year service at Mazda dealership and asked them to check / reset both keyfobs as I am changing the battery in the remote every 3-4 weeks.
Car came back with the same issue so it went back again. Was told they reset the fobs again and all was fine. Again it says battery running out but now it struggles to find the key and I have to literally hold it on the ignition button for 5 seconds for it to start. Then when driving it flashes up ignition key not found.

Have rung the dealership again but they have not called back!

Is there a simple fix I can do?
Anyone else experienced the same issues?

#2

That is the behaviour of the key when it’s battery is low. Holding it against the start button is the emergency starting procedure in the manual I think. It relies on passive RFID to transmit/receive the verification and authentication codes, much like a contactless card does.

Simple fixes? Apparently the keys are sensitive to the brand/type of battery used. I changed my own about a month ago and saw a couple of forum posts elsewhere about cheaper non-brand batteries from eBay not lasting very long. I changed it for an Energizer and it’s working ok. Try that if you haven’t already, there’s no knowing what the dealer may have put in it.

The other thing to consider is how close to the car you’re keeping the keys when it’s parked up at home. Some versions of passive keyless entry and start systems occasionally transmit from the car to the key to see if it’s close (or vice versa). This causes the key to wake up and try to exchange messages. If the key and car are close enough together that would cause the key battery to drain pretty quickly.

A quick test for that would be to park up and store the keys normally, then go back out and see if you can unlock the car with the request buttons. If you can you need to either move the key further away or put it in a faraday pouch/metal key safe. That will also reduce the cars vulnerability to relay theft.

#4

Thanks @dodger421 for taking the time to reply.

I had been using Duracell and as they were running out so quickly, I bought a pack of 6 off ebay with a longer expiry date. Not sure what the dealer used, will definitely check!

The keys are stored in a metal tin in my kitchen to avoid the car being stolen off the driveway. No issue there as even when I have the key in my hand, it does not allow me to open the door by pressing the button (on the door) and I have to repeatedly press the key fob button to get the door to unlock!

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#5

A lot of the branded batteries sold on eBay (and elsewhere) are fake. Duracell is probably faked more than most, because of its high profile.

It’s worth purchasing a battery from a known reputable seller and seeing whether that makes any difference.

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#6

Possibly a stupid question and I’ve just not read the OP properly, but is it happening with both keys or just the one?