2007 328i key fob dead.....help

[kino1161]

My son’s key fob went dead today. Is there a way to still drive it?

[g8r1fl]

Dead as in won’t lock/unlock car? If you put it in the ignition slot does it start up?


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[kino1161]

Correct. Had to use the spare slot key. Will not start car either. Can the push button be taken out?

[g8r1fl]

That’s weird. I have 3 key fobs and one died last year. Won’t lock/unlock but once I insert it it will start the car


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[kino1161]

Hmmmm….. ??

[kino1161]

Could dead car battery be the culprit?

[dworthy]

Do you have the key symbol on the dash when you try to start?

Do you hear just a click when you hit the start button?

[kino1161]

He gets nothing when he inserts the key fob into the ignition, nor does the key unlock the doors (via the buttons).

[dworthy]

Sounds like a dead battery if no lights come on the dash.

[kino1161]

Would the dead battery cause the key fob not to work even on the doors?

[WIN3Srz]

Open the door with the metal key and try jump start the car.

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[JDStrickland]

Would the dead battery cause the key fob not to work even on the doors?




Yes. Anything that is electrical will not work reliably if the battery in the car is weak or dead.

[kino1161]

Well, I jumped the car and it started. Keep the mind, I cut open the key and ordered a new shell and battery. ��. Anyway, does anyone know what the following warning lights mean? Yes, he has warning lights now. One looks like a spark plug, one looks like a red circle with a liquid in it with a parenthesis and the last is the front end of a car with a circle with exclamation point inside above the hood....with a parenthesis around it.
I can’t seem to post pics...

[dworthy]

Wait, you cut open the key to get to the battery inside? There are plenty of YouTube vidoes showing how to open the back cover to access the key's battery. IIRC the battery tend to last about 4 years on those keys.

You can also use another website to host the photos and just link it here. Sounds like you have a service due on the first one, would have to see a picture to be sure.

[White94RX]

If the car doesn't have comfort access, the battery isn't replaceable by simple means. It does require opening the fob.

[dworthy]

If the car doesn't have comfort access, the battery isn't replaceable by simple means. It does require opening the fob.

Yeah, forgot about that part, as it gets recharged like the E-46 keys inside the ignition slot.

[kino1161]

Update. Went home at lunch to check on car. Dead again! So, after letting it run forever yesterday and re-starting last night, it is dead again! Someone mentioned the failed Alternator Diodes/ Voltage Regulator. Does the symptom sound familiar? If so where do I purchase from?

[White94RX]

Modern day BMWs don’t charge batteries. They’re not made to do that. They replenish the little bit of power used to start the engine, and then simply maintain a constant voltage. If the battery in the vehicle is dead, which it sounds like it is, then it needs to be replaced.

If you can jump start the car, you can easily test the alternators output with a volt meter. My guess is that the alternator is fine, and the car needs a new battery. Don’t make it overcomplicated.


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[kino1161]

Went to AutoZone. Battery is good, alternator is bad. What are my options? I need to get him back on the road. ��

[JDStrickland]

Update. Went home at lunch to check on car. Dead again! So, after letting it run forever yesterday and re-starting last night, it is dead again! Someone mentioned the failed Alternator Diodes/ Voltage Regulator. Does the symptom sound familiar? If so where do I purchase from?


You are utterly ill equipped to deal with this. Go to the local Authorized Independent BMW Service Center and go back in a few hours and get your car back. Bring your checkbook on the return trip.

[kino1161]

Thanks! I’m new to BMW and just trying to get some guidance from those that know. I can’t possibly know what you BMW veterans know. I can assume things but I don’t because these cars a big computers. I do my own maintenance on my wife’s MB and my Cayenne but I am very new to BMW and don’t want to mess something up..... just looking for guidance and save a few dollars in the process.....but thanks again for your help.��

[White94RX]

That battery is not good. AutoZone is not equipped to properly test it. Their testers don’t put a real load on the battery. Nor can they run a diagnostic scan, including an energy diagnosis test plan.

My advice would be to replace the battery, have it registered at a BMW specialist shop, and then check the alternator. A bad battery will affect the alternator charging, or not, or even overcharging. Don’t trust autozone. They’re not trained, experienced, or anything. Minimum wage idiots usually.

[kino1161]

white94RX,
How can I rule out the battery without wasting money on a new one? This battery was purchased in May 2019. i registered it with my Foxwell with the BMW app. Thanks. for your help.

[White94RX]

Energy diagnosis test plan. That's going to require ISTA.

If it is your alternator, and that battery has been deep cycled a few times, it's probably not going to hold up. Have you charged it with a real battery charger? Or just ran the engine and expected the alternator (which is questionable as of now) to charge it?

[kino1161]

No battery charger. What's this I hear about replacing the regulator? Is that an option?

[dworthy]

The regulator is inside the DME IIRC, perhaps you are thinking about the bushes for the Alternator?

[White94RX]

If the alternator is bad, just get a replacement. But like I said, you need to do more testing and confirm what’s bad and what’s not. Do you have a multimeter? A cheap one can be bought for about 15 or 20 bucks. You’d be surprised at how much you end up using it.


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[kino1161]

I checked the battery with a multimeter and it read 1.2 with the car off....I jumped it and it read 13.5

[White94RX]

Boom. Battery trashed. Alternator good.


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[kino1161]

Update. Replaced alternator and everything is working fine now. Thanks, all, for your knowledge and input.

[White94RX]

Lol. So you replaced the alternator even though it was working perfectly?


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[kino1161]

My mechanic said the alternator was not operating properly under load.

[Harrisonkelsie]

Do you have the key symbol on the dash when you try to start?

Do you hear just a click when you hit the start button?

What does the key symbol with the dash through it mean or what can cause this? I have it on right now.