Share Car key fob battery

[dburanich]

For those of you that have changed your fob batteries.
If you have any programmed fobs so to speak that reset mirrors and seats to a certain position, is any re-programming needed on this type after a battery change?

 

[Palouse]

For those of you that have changed your fob batteries.
If you have any programmed fobs so to speak that reset mirrors and seats to a certain position, is any re-programming needed on this type after a battery change?

I bet every car is different!

 

[MikEm13]

I believe that programing is kept in the body cpu (car body). So changing the battery in you key fob shouldn't be affected.

 

[gchappel]

I have to change the fob batteries for our Jeep grand cherokees about every 2 years. Car tells us when they are low.
At least in the jeeps, you do not have to reprogram anything. Just pop in a new battery and go.
Our local bulbs and batteries store will change batteries in 2 fobs for the life of the car for $15. Sometimes I am lazy- so now I just walk in when one is low, and they change the batteries in both of them.
gary

 

[Ogof Mole]

My Nissan Note is now ten years old, never changed a key battery.

 

[McQ]

Car Nissan Xtrail Tekna

When was the last time you put ,or the garage replaced the battery (wireless type) in your car key fob? I got to thinking about it, when the car goes in for a service they only take one set of keys. Therefore on that basis one set or both never get the battery replaced. In mine it is a small round CR button battery which has been in them for 6 years.

So decided to order new batteries to be on the safe side, don't want them to pack up suddenly. There is a manual normal emergency key within the fob but that only opens the doors, bit pointless if you can't start the car with it.
So it actually took to reading the handbook as to how to change the battery ,even that took some finding, came under maintenance not the key section.car key fob battery

For my car, it won't ever need that because there's no fob (although fobs are optional). My cellphone is my key. The backup is a black credit card that I keep in my wallet that also opens the doors and runs the car. (Tesla Model 3)


Replaced my fob battery (for my wife's car) about two months ago because it died. Very easy to do, and well worth staying on top of. Good reminder, Barry.

 

[frdjohns]

For those of you that have changed your fob batteries.
If you have any programmed fobs so to speak that reset mirrors and seats to a certain position, is any re-programming needed on this type after a battery change?

In my Ram, changing the battery in the key fob had no effect on the memorized seat position. In fact, changing the battery in the vehicle had no effect on it either. Once set, it stays memorized until changed.

 

[JeeperDon]

In my Ram, changing the battery in the key fob had no effect on the memorized seat position. In fact, changing the battery in the vehicle had no effect on it either. Once set, it stays memorized until changed.

In Chrysler vehicles, the Central Timer Module (CTM) is a box usually located on the kick panel on the left side. The key fobs all just have a unique hard coded number, which is programmed into the CTM by a dealer (no "do three on/off key cycles while rub your tummy" tricks). I had to swap the CTM a couple times on my 20 yr old Durango and had to pay a dealer to get the fobs to work.

 

[Lucky Duck]

Bah... never had to worry about any of this fangly stuff when we had hand cranks!

 

[JLH]

Some years back when fobs just opened the doors (well, signaled the vehicle to do that) they were easy on batteries. Today's cars with many more functions drain batteries much faster due to them using radio waves to communicate to the vehicle even before you touch the car. While my 2001 Nissian Xterra was able to go over ten years on the original batteries I don't expect my newer keyless entry vehicles to do that. On our '15 Honda Fit EX-L I replace the batteries every two years or so. Mostly it depends on how much we use the car. Some store their keys close to their cars and learn the hard way that will cause the fob to drain its battery in a few months, not years.
Luckily its normally a simple job to put in a new battery. Most use very common 2032's that are available everywhere and are low priced. I always use quality name brand (the gold and black one) and avoid cheap batteries. Also, when you change the battery you likely will not have to reprogram the vehicle. Well, that is true for most all cars. There are exceptions. With some vehilcles you can do the programing yourself, a few vehilces require a special tool to perform this. Some shops like "Batteries +" have the tools. With other vehicles you may have to see your dealer. I always advise people to research this BEFORE they change the batteries! There is a lot of information available about this on-line.
For the starter function most cars do have a way to allow the vehicle to start should the fob battery go dead. I advise people to make themselves familiar with those instructions BEFORE they need to know them!

 

[TonyW]

Interesting, my BMW will be 3 years old in August and already showed key fob battery low warning on dash display! Replaced both main and spare. I can only guess that the transponder chip must place a small load on the battery constantly. Also have to keep fobs in a Faraday bags overnight due to the risk of high tech thieves wanting steering wheels and airbags - poor neighbour lost both on two separate occasions

Years ago my mother asked me to get a replacement key for her Peugeot due to original falling apart. Took the car in for service at a main dealer and was quoted £56 for a replacement. Bought two from EBay and batteries for about £5.

 

[Growltiger]

Interesting, my BMW will be 3 years old in August and already showed key fob battery low warning on dash display! Replaced both main and spare. I can only guess that the transponder chip must place a small load on the battery constantly. Also have to keep fobs in a Faraday bags overnight due to the risk of high tech thieves wanting steering wheels and airbags - poor neighbour lost both on two separate occasions

Years ago my mother asked me to get a replacement key for her Peugeot due to original falling apart. Took the car in for service at a main dealer and was quoted £56 for a replacement. Bought two from EBay and batteries for about £5.

I understood that - at least nowadays - only a dealer can program a new key to the car. So how did you do it?

 

[TonyW]

I understood that - at least nowadays - only a dealer can program a new key to the car. So how did you do it?

You are probably correct about dealer only programming, but I did not need to program anthing as the original key was not lost. All I did was purchase a couple of Peugeot replacement keys and batteries and move the original transponder from the old and broken key to the new ones. As far as I am aware spare keys are easy to get at a fraction of the cost of dealership (at least our local dealership - in my case around £5 for two against £56 dealer quote) and as long as you have the original transponder you should be good to go.

Interestingly, the thieves that attacked my neighbours cars use a cheap device to contact and copy the key codes from a key somewhere in the house and then have the means to program keys if they steal the car. In this case they were not interested in the cars but the steering wheels and airbag assembly that can cost over £2k for a genuine source. From what I can see these are then listed on sites such as eBay at a quarter of the new price and at the time I looked were listed as being in Latvia, Lithuania although delivery was quoted as being within a week of purchasing.

 

[Growltiger]

You are probably correct about dealer only programming, but I did not need to program anthing as the original key was not lost. All I did was purchase a couple of Peugeot replacement keys and batteries and move the original transponder from the old and broken key to the new ones. As far as I am aware spare keys are easy to get at a fraction of the cost of dealership (at least our local dealership - in my case around £5 for two against £56 dealer quote) and as long as you have the original transponder you should be good to go.

Interestingly, the thieves that attacked my neighbours cars use a cheap device to contact and copy the key codes from a key somewhere in the house and then have the means to program keys if they steal the car. In this case they were not interested in the cars but the steering wheels and airbag assembly that can cost over £2k for a genuine source. From what I can see these are then listed on sites such as eBay at a quarter of the new price and at the time I looked were listed as being in Latvia, Lithuania although delivery was quoted as being within a week of purchasing.

Thanks, that makes sense.
I have read of people keeping their keys in an earthed faraday cage to prevent that method of theft. It doesn't really copy the codes, it just acts rather like a wifi extender, so the car thinks the fob is right next it.

 

[TonyW]

Thanks, that makes sense.
I have read of people keeping their keys in an earthed faraday cage to prevent that method of theft. It doesn't really copy the codes, it just acts rather like a wifi extender, so the car thinks the fob is right next it.

I think that things are much more sophisticated now particularly keyless cars. The devices for copying the code are cheap and available and very quick and easy to clone a key once in the car. At least according to my dealer when discussed a couple of years ago. This may be of interest
https://www.driving.co.uk/news/features/six-ways-thieves-can-break-into-a-car-and-how-to-prevent-it/

 

[Growltiger]

I think that things are much more sophisticated now particularly keyless cars. The devices for copying the code are cheap and available and very quick and easy to clone a key once in the car. At least according to my dealer when discussed a couple of years ago. This may be of interest
https://www.driving.co.uk/news/features/six-ways-thieves-can-break-into-a-car-and-how-to-prevent-it/

Very interesting, thanks. I only knew about relaying. The security weakness of the diagnostic port shows how little grasp of security the manufacturers have.
Communications to the fob should be made to use standard authentication methods, with a two way communication and a different reply each time.

 

[Ogof Mole]

But if manufacturers increase their security, less cars will get stolen, which means that they will sell less cars as replacements (Not so good for profits).

 

[Clix Pix]

After reading this thread I have now ordered a couple of Faraday pouches to protect my key fobs when at home and also when (eventually) I'll be traveling again..... We have had a few situations of vandalism and break-ins on cars here in our parking lot and my condo unit is one which faces out on to the parking lot so that it is conceivable that someone with a device could pick up the signals from my key fobs even inside my dwelling. Better safe than sorry, eh?!