'07 E92 Keyfob (non CA) suddenly stopped working

E92_BGDoc · 10-20-2020, 01:47 AM

A few days ago i hooked up a battery charger to top up the battery of my e92 as the car was not driven for about a week. After the charging was complete i disconnected the charger and locked the car as usual, using the lock button on the key fob. So far so good. Then after around 4 days i needed to use the car but when attempting to unlock it... not one of the three buttons on the key would not do anything, all were completely dead. My first thought was perhaps a glitch, so i opened the car using the old school manual key. Car started fine with the keyfob put in the slot and drove the car for about 30 mins. However, after that the buttons still did not work, and haven't worked ever since. This is what i have done so far:

- First thought was dead keyfob battery - cut the key open to measure good 3.2V, falling to 2.7V when pressing a button. Just to be 100% sure i took it to a locksmith who confirmed there is wireless signal being transmitted, hence it is highly unlikely the problem is in the key itself

- Checked all fuses related to central locking + fuse F2 (Diversity antenna) and all looked intact

- Went to the local junkyard to replace the diversity antenna module with another one - still nothing. The module itself looked pristine, no sign of water ingress. Also, radio works fine for both FM and AM bands.

- Read out error memory via INPA - no errors.

The car came with 2 keys but only one functioning, i suspect because the battery of the second one is dead as it was not being used at all. I am a bit lost to what might be the problem, any help will be greatly appreciated

jarsdad1 · 10-20-2020, 05:55 AM

while the locksmith tested the key and said the battery was LIKELY not the problem, I would invest $5-6 in a couple of new key batteries. If that does not solve the problem, you still gave two fresh keys when you do.

53N30W · 10-20-2020, 12:53 PM

I went through this awhile back on a 07 328 Non CA. You can't replace the battery on a non CA key unless you cut the case apart and then glue it back together. There are some articles on this if you do a search . Dealer wants $200 for a new fob, you keep the metal key.

jarsdad1 · 10-20-2020, 02:13 PM

Quote:

Originally Posted by 53N30W

I went through this awhile back on a 07 328 Non CA. You can't replace the battery on a non CA key unless you cut the case apart and then glue it back together. There are some articles on this if you do a search . Dealer wants $200 for a new fob, you keep the metal key.

OP said he cut the case already on the one key and the spare never worked.

E92_BGDoc · 10-23-2020, 02:42 AM

After all the trial and error the problem was resolved - apparently some of the keyfob's electronics went out and the transmitted signal was corrupted. After opening and replacing the battery of the second one (which was dead for a long time) it started to work right away, car can now be remotely locked and unlocked with no issues.

10-20-2020, 01:47 AM	#1
E92_BGDoc New Member 2 Rep 13 Posts Drives: 2007 E92 325i Join Date: Jun 2019 Location: EU iTrader: (0)	'07 E92 Keyfob (non CA) suddenly stopped working A few days ago i hooked up a battery charger to top up the battery of my e92 as the car was not driven for about a week. After the charging was complete i disconnected the charger and locked the car as usual, using the lock button on the key fob. So far so good. Then after around 4 days i needed to use the car but when attempting to unlock it... not one of the three buttons on the key would not do anything, all were completely dead. My first thought was perhaps a glitch, so i opened the car using the old school manual key. Car started fine with the keyfob put in the slot and drove the car for about 30 mins. However, after that the buttons still did not work, and haven't worked ever since. This is what i have done so far: - First thought was dead keyfob battery - cut the key open to measure good 3.2V, falling to 2.7V when pressing a button. Just to be 100% sure i took it to a locksmith who confirmed there is wireless signal being transmitted, hence it is highly unlikely the problem is in the key itself - Checked all fuses related to central locking + fuse F2 (Diversity antenna) and all looked intact - Went to the local junkyard to replace the diversity antenna module with another one - still nothing. The module itself looked pristine, no sign of water ingress. Also, radio works fine for both FM and AM bands. - Read out error memory via INPA - no errors. The car came with 2 keys but only one functioning, i suspect because the battery of the second one is dead as it was not being used at all. I am a bit lost to what might be the problem, any help will be greatly appreciated
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10-20-2020, 05:55 AM	#2
jarsdad1 Private First Class 55 Rep 172 Posts Drives: 2011 535i, 2015 X1 3.5 Join Date: Oct 2016 Location: Philadelphia, PA iTrader: (0)	while the locksmith tested the key and said the battery was LIKELY not the problem, I would invest $5-6 in a couple of new key batteries. If that does not solve the problem, you still gave two fresh keys when you do.
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10-20-2020, 12:53 PM	#3
53N30W Enlisted Member 20 Rep 45 Posts Drives: 2009 E92 328 Join Date: Nov 2012 Location: Pompano Beach FL iTrader: (0)	I went through this awhile back on a 07 328 Non CA. You can't replace the battery on a non CA key unless you cut the case apart and then glue it back together. There are some articles on this if you do a search . Dealer wants $200 for a new fob, you keep the metal key.
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10-23-2020, 02:42 AM	#5
E92_BGDoc New Member 2 Rep 13 Posts Drives: 2007 E92 325i Join Date: Jun 2019 Location: EU iTrader: (0)	After all the trial and error the problem was resolved - apparently some of the keyfob's electronics went out and the transmitted signal was corrupted. After opening and replacing the battery of the second one (which was dead for a long time) it started to work right away, car can now be remotely locked and unlocked with no issues.
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