[clix]

Here's a quick how to, with pictures, for replacing the MX-5 Mk3 battery in the remote keyfob unit.

1. Firstly, your key should look like this.

2. Look closely at the key recess, there's a small plastic hole and tab.

3. Insert a small flat bladed screwdriver into the hole and carefully but firmly push the main "remote" unit down and away from the top "key section" as shown.

4. The two sections should come apart easily from this point.

5. Let's take a closer look at the main unit body. See the white triangle? It's pointing to a recessed tab shown by the red arrow in the picture. Use the small bladed screwdriver to lift the top section apart. It's quite tricky if the unit has never been opened before.

6. You should now have two halves. Note the battery location and the polarity. Very gently, flip the battery out with the screwdriver.

7. Ping! The battery type is a CR1620 3V cell. Often found at watch repair or key cutting shops. They're usually cheaper per unit online, though you may wind up buying several.

8. Pop your new battery in place, again remembering the polarity. It should be as shown: negative side up, positive side down.

9. Fix the two halves of the "remote" section together firmly.

10. Slide the "key section" back onto the "remote" section and you're done.

All attached thumbnails in sequence:

 

[safetymatch]

Ahhh, i think my batteries in both keys have just about had it, will get 2 this week, i was worried incase the key would lose it's code if the battery was removed for any length of time.

 

[MX5_Owner]

Ahhh, i think my batteries in both keys have just about had it, will get 2 this week, i was worried incase the key would lose it's code if the battery was removed for any length of time.

No...one of my keys was not working at all when I got Bob... and the other one was sketchy at best.

I changed the batteries not long before xmas.... and both work just fine. So that was at least 7 months one was not working at all until I changed battery.

 

[Harco]

My key battery went flat a few months ago and subsiquently was placed in a cupboard until last week when I changed the battery and it worked straight away, no need to recode

 

[MX5_Owner]

I think, like all other keyfobs they have EPROM memory (not EEPROM) which means it's hardcoded until programmed out.....

 

[safetymatch]

Good news, i'm getting to the stage where i have to tap the key in my hand to make it work.

 

[safetymatch]

Both keys died yesterday so a trip to Halfrauds £7.98p and 10mins later both keys are now back in action.
I suspect these batteries have a life span of 5 years as both batteries died at the same time, more or less.

 

[Pat]

Just don't damage the key and fob cos its £230 to replace

 

[badman]

Just don't damage the key and fob cos its £230 to replace

Shock & horror

 

[daren_newbury]

thats more than my first car

 

[Jot]

thats more than my first car

ditto :nod:

 

[TheGrifter]

This worked a treat - Totally spot on Chris - 30seconds for each key fob once you prized the bits apart. Batteries seem to fade after 4 years.

 

[clix]

This worked a treat - Totally spot on Chris - 30seconds for each key fob once you prized the bits apart. Batteries seem to fade after 4 years.

Cool. Yes, 4 to 5 years is about right. :thumbsup:
I think this was one of the first small articles that I wrote for mx5life. Didn't take a lot of doing but curiously...
Since I wrote it, we've had an enormous amount of google searches that land on this page, all searching for: mx5, battery, remote, cell, replace - those kinda keywords.
All good.

 

[Nigel]

Excellent guide, Clix.
:thumbsup:

 

[GlasgowDave]

One thing that I would say is that the contacts to the battery can get slightly displaced over time. This'll happen when the battery is low and you begin to press the buttons harder. I have had a couple of incidences of replacing a battery only to find poor performance from the fob still. What to do is gently push the contacts out a little to make sure they'll make good contact with the battery. But don't push to hard and break them. I hear it's £230 for a new one!

Dave

 

[quiny]

One thing that I would say is that the contacts to the battery can get slightly displaced over time. This'll happen when the battery is low and you begin to press the buttons harder. I have had a couple of incidences of replacing a battery only to find poor performance from the fob still. What to do is gently push the contacts out a little to make sure they'll make good contact with the battery. But don't push to hard and break them. I hear it's £230 for a new one!

Dave

good advice dave.
i have had the same problem with my remote fob in the past

 

[AnotherMissedApex]

Great stuff Clix. The photos were really helpful - like a perfect Haynes manual entry.

My battery went after 4.5 years - right on target.

My local key cutter had the batteries for £2.50 each i.e say 50p a year or 1/7 p per day!

 

[elan-sprint]

My remote fob was showing signs of reluctance to waken up (apologies to any neighbours who were concerned for my welfare if they saw me performing a strange dance around the car each morning!), and I was about to replace the battery. I even went as far as preparing to sacrifice a frozen chicken to the Great God SNAFU in the hope that it would appease him and I wouldn't end up with a painful bill for a new fob, but for some unfathonable reason, I decided to phone my Mazda dealer first!

Shock, horror! They quoted me just over £8 (all inclusive) to replace the battery and perform a quick test to make sure all the other gubbins were of sound body and mind. They didn't even demand that I book an appointment sometime next year, or leave the car with them for the day!

I drove in, handed over the fob, grabbed a free cup of coffee, and the empty cup had hardly hit the bin when the fob was returned to me. Job done!

I've often been frustrated by the rip-off attitude of many main dealers (not just Mazda) but, unless I just happened to be exceptionally lucky (or the Great God SNAFU was pleased that I'd at least considered making a sacrifice!), it might be worth while checking the dealer in your area if you have any concerns about making a Horlicks of the job!

 

[Pat]

We always get ours done at main dealer

Main Dealers can surprise you sometimes :nod:

 

[badman]

Less than £2 off flea bay for two batteries

Less than 5 minutes of my time to fit.

Bargain. :thumbsup: