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hello every one, I own a couple of bmws one is a 328i 2011 and the other one is a 2003 525i,wich brings me to ask a question for you.On the 525i 2003 I am replacing the original m steering wheel for the m flat bottom one , I look at the videos on youtube on how to do it, and it looks very easy, however no long ago I unplug the battery for some reason, and I connected it two days latter, the car would not start. I end up towing it to the dealership and I paid $1100.00 dollars and they kept the car for 2 weeks.The said they had to reset all car codes.
So now I am afraid to disconnect the battery and find out that the car would not start. I was going to use one of those code savers, but will the air bag diploid? since the system has electric current? I thank you for your advice.
 

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Hi and welcome to Bimmerfest :wave:.

I'm afraid in your instance there is no safe alternative but to disconnect the battery before unplugging the airbag, there are plenty of people out there that will probably disagree but there's no way I'm advocating that. Last time I suspect what really happened was that when the battery died it may have been weak to start with and was out sufficiently long enough that the alarm system became "un-synced" to the DME which was the reason the car wouldn't start, normally disconnecting the battery for short periods shouldn't be a problem, I've had mine disconnected for up to a week with no issues yet I've read other instances where people have only had them out for a day or two and this has happened but most of them had weak batteries to start with.
If your worried about it, it may be possible to disconnect the battery, take your steering wheel off and then (depending on what your working on) reconnect the airbag before reconnecting the battery (tie the airbag up, don't let it hang from its own wiring), this way you can work on the wheel yet still have the car connected to power. Then do the same when your ready to put the wheel back in i.e. disconnect the battery, then fit the wheel/airbag etc. You'll still get a few error codes I suspect along with the clock needing to be reset and active steering (if you have it).
I'm not 100% certain on this with your car so throw up a post here, these guys will know if it possible to go this route or not.

I'd strongly advise investing in the BMW software suite be it DIS or the newer ISTA suites (in fact since you also have an 2011 car I'd say ISTA), this will allow you to diagnose problems and run test plans for them if needed, clear codes and make backups of all your existing modules and coding etc etc, it will save you a fortune in garage fees in the long run and is available all over the place ebay, amazon and a whole load of dedicated vendors that deal with BMW software, there'll be a learning curve involved if you've never used this before but it's absolutely worth it for these cars.

As a side note, if your ever worried about your battery then use a voltage meter on the jump terminals in the engine bay, with the engine off but ignition and lights on your looking for over 12v (mine has always sat at 12.25v since I bought it), with the engine running you want about 14.5 give or take a bit, anything less than that 12v is inviting problems and the battery wants a charge.
 
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