Car key fob - new battery? e46 330ci

[rharris21]

My key fob at the moment is either not working at all, or it works all the time.
It never works standing lets say another car length away from the sensor.
I always have to stand fairly close to the sensor.

I am not sure but one day it just suddenly stopped working. Even standing right up close to the sensor it just would not open.
Then the next day it may open and lock all day long?

I am under the illusion that the battery in the key fob charges whilst the car is driven.
Well I did a 200 mile round journey twice last week and it didn't work at all on one day.. The other day was random, sometimes it worked and sometimes it didn't.

Could it be the sensor in the mirror that is faulty?

Anyone else experienced this?

Any help is greatly appreciated.

[tgr]

Key does indeed charge up when in the ignition. You should through careful observation be able to narrow it down either to the key or the receiver. Do you have another working key with which to compare? New keys are about GBP 140 and new receivers are I think about GBP 400 all in

[rharris21]

tgr said:

Key does indeed charge up when in the ignition. You should through careful observation be able to narrow it down either to the key or the receiver. Do you have another working key with which to compare? New keys are about GBP 140 and new receivers are I think about GBP 400 all in

No unfortunately not I do not have a spare key.. which is why I guess its even more frustrating. I wanted to get a spare key anyway but not in this fashion! How can I tell which it is i.e. key or sensor?

[tgr]

Good question! I would keep on the way you're doing observing what happens on long trips ie when the key has time to charge up so unlikely to be the source of the problem. The cheapest solution is to replace the rechargeable battery in the key which you can do yourself if you're handy or have a friend who's good with a soldering iron. If you google BMW diamond key fob you'll find a step by step guide. Once you've done that then you either will have a fully working key, or a key that is still on the blink because it has nothing to do with the battery, or the receiver is duff.

I should add this is a common E46 problem. Mine is ten years old and a key has died, luckily I have another. I have a good indy though - if you can't narrow down the problem a trip to yours is well advised.

How old is the car?

[rharris21]

tgr said:

Good question! I would keep on the way you're doing observing what happens on long trips ie when the key has time to charge up so unlikely to be the source of the problem. The cheapest solution is to replace the rechargeable battery in the key which you can do yourself if you're handy or have a friend who's good with a soldering iron. If you google BMW diamond key fob you'll find a step by step guide. Once you've done that then you either will have a fully working key, or a key that is still on the blink because it has nothing to do with the battery, or the receiver is duff.

I should add this is a common E46 problem. Mine is ten years old and a key has died, luckily I have another. I have a good indy though - if you can't narrow down the problem a trip to yours is well advised.

How old is the car?

Thanks for the advise. So far today, the fob has worked instantly every time I have tried it. Most perculiar. And I haven't been on a long journey all week..
My car is coming up to 10 years old also. I personally don't have a soldering iron etc to replace the battery. I have seen that guide and wouldn't try it myself as I know I would ruin it.

really don't want to replace the receiver as I am looking to change the car soon. I take it the receiver is only a BMW job?

[nottyash]

There is an advert on ebay where you send your key in, they replace the battery and sender unit for about £30. You get a refund if it doesnt work minus postage.

[CypherP]

nottyash said:

There is an advert on ebay where you send your key in, they replace the battery and sender unit for about £30. You get a refund if it doesnt work minus postage.

No disrespect to your post, but I wouldn't trust anyone to do anything with my key, other than the manufacturer. Especially if having to send the key to someone with no guarantee of it ever coming back to you!

OP, if I were you, I'd pop down to a BMW service centre and tell them what the problem is and just see whether they can advise on what the issue might be. Yes, they may try and tell you that you need a new fob/sender unit or that they need to run diagnostics, but the times i've popped down with some minor issues, they have always been really helpful in that respect.

[nottyash]

CypherP said:

nottyash said:

There is an advert on ebay where you send your key in, they replace the battery and sender unit for about £30. You get a refund if it doesnt work minus postage.

No disrespect to your post, but I wouldn't trust anyone to do anything with my key, other than the manufacturer. Especially if having to send the key to someone with no guarantee of it ever coming back to you!quote]



Well go to the BMW main dealer and pay £400. Job done