Hi,can anyone help me my mx5 2.5 2002 fob is playing up it will not unlock from outside but unlocks and locks when I use from the inside if I use the key to unlock the doors my alarm goes off


The remote unit that pairs with the fob is inside the car behind the glovebox. Perhaps the signal is weakened by a tired battery but enough to work when inside car.

I would change the remote battery or at least check the voltage is around 3.0 volts.  

Put new battery in but it was a cheap make will go get another brand asap thanks


A couple of years ago I bought a pair of 2032 cells at the local corner shop for the kitchen scales, these lasted a fortnight, and close examination showed they were not Duracells but fakes.  Proper cells (Duracell, Panasonic, etc) usually last well over two years in the scales.

Both the new fobs for our Mazda3 had a dead cell at about 18 months, despite the spare one living in a steel filing cabinet and unable to talk with the car!  The Mazda3 knew when the cell was low and asked for it to be changed!  Same fob as for the ND.

The NC fob cell tends to last for a bit longer maybe 24-30 months.

In each case with the fobs the cell tested at the correct voltage with a meter (almost no current), 3v, but having lost charge over time it could not source enough current to transmit - just like when an old car battery can no longer turn over the engine.

There are also a lot of fakes and out-of-date cells about, daft when one considers how cheap the good ones are.


I’ve seen a few comments recently about rogue cheap button batteries being sold - perhaps you were unlucky enough to buy one of those.

A voltage test with a multimeter, if you have one, should show if the battery any good.   

Just read Richard’s post above, so it seems that a voltage test will not work:-(  

Last new battery for the fob I bought was several years ago, from a local dealer. Keep thinking I really should change it, but while the thoughts there, the effort isn’t!

Bit like the toothpaste syndrome! The intention is there, but I forget - till it runs out!

loulou62, are you saying that the keyless entry transmitter works when you are sitting inside the car but doesn’t work properly if you are outside it?

Hi yes that’s correct the boot opens from outside but it doesn’t open or close the doors from the outside,if I sit in the car and use the fob it opens a closes the doors don’t know what’s going on,if I try to unlock it with key it opens but the alarm goes off not good in the morning.