[uhaulball]

I'm referring to the keyless fobs that the newer bmw's use to start the engine. isn't it easy to use a fbo to activate any car? is it a specific frequency in the fob that starts it. how does the mechanism work; at first i thought it might be frequency, but i realize the cheapo spare fob/key also works to start the engine, but it doesnt seem to have any electronics in it.

[ACZakka325i]

they are programed for each car individually. Other keys will not work on your car and vise-versa

[uhaulball]

but the spare/plastic keys dont have any eletronics in em do they? and they start the car too.

[ACZakka325i]

i assume that the spare one also has been programed ,or else it wouldnt work.

anyone else care to shed some light on this topic?

[ex-poster]

Not speaking from direct knowledge of the BMW setup, hopefully someone else can fill in with the BMW specifics... but the plastic key itself has to have has a passive RFID chip in it. The fob in this particular case is to carry the key into proximity to the reader in the dash. RFIDs can and do have millions of codes, so it's not just a matter of being tuned to a specific frequency.

The normal fob has not only the RFID but the transmitter for the door locks, it gets charged by placing it into the slot. Those with CA will have to comment on how those fobs get charged...

[jflecha]

If your refering to the spare FOB in the glove box (valet key) the plastic key has to be in it to work.

Common sense will tell you that each FOB is programmed for each individual car.

I'm FOB'd out.

[Steve P.]

The plastic key does have a chip in it..... which is specifically programmed to each car.

[sdorn]

Originally Posted by smithrh

Those with CA will have to comment on how those fobs get charged...

You have to put it in the ignition slot like you don't have CA in order to charge the fob when the batteries die. My salesman said I needed to plug it in about once a week to keep it charged.

[Ghunger]

Actually, if you have CA you need to replace the batteries periodically. without CA it recharges. Unless the car manual is wrong...

As for the fob, I'm sure it, like most keyless entry fobs, probably uses encrypted codes so it's almost impossible to fake the right code.

[3aficionado]

1. Plastic fob in glove box need the plastic key to work - the combined plastic fob and plastic key fits into the dash to start car.
2. Plastic key contains the information that is need by the dash receiver to start car. Plastic fob has no electronics that work the doors, etc. The plastic key must be used for door unlocking in the event you don’t have a keyfob.
3. The CA fob has a battery door on the back and batteries must be changed regularly. When the battery (signal) gets weak the instrument panel will tell you the battery is getting low and needs changing. The CA fob does not recharge in the dash.
sdorn, tell your dealer to read the manual or use the car before passing misinformation to their customers.
4. The non-CA fobs have rechargeable battery (no battery cover on the back) and need to be inserted every few weeks to maintain charge.
5. The fob uses a rolling code. The fob sends a signal to the car the car receives it and sends a signal to the fob and then the fob sends another signal to the car. IIRC not very easy to duplicate.

BMW and Mercedes have used similar features in the past by adding electronic codes to keys. These electronic codes are why most stolen Mercedes and BMWs are taken by force. Car jacking to get the keys is the only way a thief is going to drive your BMW.

The only security difference between the coded keys of the last few years and BMWs fob is the implementation of the dash insert instead of a key insert. This system is safer than any key otherwise BMW and Mercedes wouldn't have CA or KeylessGo on their most expensive automobiles (7 series/SL).

[sdorn]

Well that would be stupid to put rechargeable batteries in one and non-rechargeable batteries in the other.

[3aficionado]

Originally Posted by sdorn

Well that would be stupid to put rechargeable batteries in one and non-rechargeable batteries in the other.

Read your manual. That’s the way it is. This is an old debate and I’m sure you can join that thread by searching for it.

The general consensus is BMW didn’t want to ask customers who paid extra for CA to have to put their key in the dash every few weeks to recharge. One of the selling points of CA is not having to place your fob in the dash. So twice a year or so your car will tell you to change the battery in the fob.

Those who are always placing their fob in the dash (non-CA customers) are getting a charge so its one less inconvenience for them. But they do need to use their spare fob every couple months to keep a reserve charge on that fob - which seems like a pain to ask a driver to dig out their spare fob every few months to maintain a charge just in case they need the fob down the road.

[sdorn]

Originally Posted by 3aficionado

The general consensus is BMW didn’t want to ask customers who paid extra for CA to have to put their key in the dash every few weeks to recharge. One of the selling points of CA is not having to place your fob in the dash. So twice a year or so your car will tell you to change the battery in the fob.

Stupid salesman. Why would he think I need to recharge the damn thing. I have been sticking it into the ignition for no damn reason. Dumb ass.

So is replacing the battery covered under the maintenace warranty, or do I have to buy them?

[3aficionado]

Originally Posted by sdorn

So is that covered under the maintenace warranty, or do I have to buy the batteries?

Not covered under any warranty. I guess it would fall under the normal wear and tear clause. You dont expect BMW to refill your gas tank when it drains, do you? Hopefully you can afford $5 every 6 months or so for a battery.

[uhaulball]

Originally Posted by 3aficionado

Read your manual. That’s the way it is. This is an old debate and I’m sure you can join that thread by searching for it.

The general consensus is BMW didn’t want to ask customers who paid extra for CA to have to put their key in the dash every few weeks to recharge. One of the selling points of CA is not having to place your fob in the dash. So twice a year or so your car will tell you to change the battery in the fob.

Those who are always placing their fob in the dash (non-CA customers) are getting a charge so its one less inconvenience for them. But they do need to use their spare fob every couple months to keep a reserve charge on that fob - which seems like a pain to ask a driver to dig out their spare fob every few months to maintain a charge just in case they need the fob down the road.

spare key meaning, the 2nd fob right? not the cheapo/plastic fob.

[3aficionado]

Originally Posted by uhaulball

spare key meaning, the 2nd fob right? not the cheapo/plastic fob.

Yes, in that instance by spare key I was referring to the second fully functional keyfob. Sorry for the confusion.

[itznin]

Forget this spare key nonsense....

The bottom line here is, the car is HARD TO STEAL..

Can it be stolen? sure by high tech guys who have the electronics to crack your ignition code...

[3aficionado]

Originally Posted by sdorn

Stupid salesman. Why would he think I need to recharge the damn thing. I have been sticking it into the ignition for no damn reason. Dumb ass.

Unfortunately its rare to find a salesperson who knows more about the e90 than the people on these boards. When you read through the posts you will see lots of bad information passed out by salesmen. Best thing to do is ask the question here or look through the manual.

If you go to page 28 of the manual you will see printed, "In cars equipped with convenient access, the remote control contains a replaceable battery, refer to page 37." Page 37 has detailed instructions for replacing the battery.

Post- Sept Manual: https://www.e90post.com/forums/showthread.php?t=5075

[sdorn]

Originally Posted by 3aficionado

Unfortunately its rare to find a salesperson who knows more about the e90 than the people on these boards. When you read through the posts you will see lots of bad information passed out by salesmen. Best thing to do is ask the question here or look through the manual.

If you go to page 28 of the manual you will see printed, "In cars equipped with convenient access, the remote control contains a replaceable battery, refer to page 37." Page 37 has detailed instructions for replacing the battery.

Post- Sept Manual: https://www.e90post.com/forums/showthread.php?t=5075

Yeah, I went and got my manual out earlier when I read your first post. I had already read the section about the battery, but I just assumed it meant that the rechargeable battery needed to be replaced from time to time. I had no reason to believe my salesman didn't know what he was talking about, and the manual doesn't specifically say that the battery isn't rechargeable. It just says it needs to be replaced from time to time.

The manual doesn't say how often it needs replacing. Where is everyone on here getting the "twice per year" time? I have had remote control fobs for cars for years, and I have never had to replace the fob battery more often than once every three - five years. I realize this fob is a little more active, with it needing to be able to respond when it receives a signal from the car. I guess that sucks the battery down much faster.

[E90Fleet]

Originally Posted by sdorn

Yeah, I went and got my manual out earlier when I read your first post. I had already read the section about the battery, but I just assumed it meant that the rechargeable battery needed to be replaced from time to time. I had no reason to believe my salesman didn't know what he was talking about, and the manual doesn't specifically say that the battery isn't rechargeable. It just says it needs to be replaced from time to time.

The manual doesn't say how often it needs replacing. Where is everyone on here getting the "twice per year" time? I have had remote control fobs for cars for years, and I have never had to replace the fob battery more often than once every three - five years. I realize this fob is a little more active, with it needing to be able to respond when it receives a signal from the car. I guess that sucks the battery down much faster.

CA battery is supposed to last 2 years with "normal use"

[sdorn]

Originally Posted by E90Fleet

CA battery is supposed to last 2 years with "normal use"

That seems reasonable. At least now I know I don't have to keep sticking it in the ignition for no reason.

[Broken1]

Originally Posted by E90Fleet

CA battery is supposed to last 2 years with "normal use"

I believe this is correct.

I've had my car for 7 months, and my fob is still going strong - so that throws out the 2ce a year story (ie once every 6 months)