[rusty_g80]

I took my car to dealer for mat sensor recall. They replaced the mat sensor which took 3 days (said first one did not work, so they installed another one). Now there is an air bag light on that keeps coming back. Also the receipt says that "after programming there was a fault for battery safety terminal". Does that mean they screwed up my battery safety disconnect that costs like $1K to replace?

[X_Drive]

The battery safety cable is the pyrotechnic device that disconnects the battery from the engine electronics in the event of a serious collision. It can set an airbag warning light if it is defective or corroded.

This may be a dealer issue, however, in most cases sometimes things like this occurs by coincidence. May I ask if your battery has been replaced by someone other than a dealer?

[PhaseP]

The BST is on the battery positive terminal, which is in the trunk. I doubt they would have done anything related to it while changing matt sensor.

The tiny connection that goes into the BST is not very sturdy if ever removed once. I had removed it when changing battery by mistake, and I started getting air bag light after a while that. As solution I made the prongs on this tiny connector widened up a bit with a flat screw driver so that it would securely attach. Also cleaned the male and female parts with contact cleaner and put it back. I had also cleaned up steering air bag connections at the same, those were my two suspicions. I don't have the light any more.

[X_Drive]

Originally Posted by PhaseP

The BST is on the battery positive terminal, which is in the trunk. I doubt they would have done anything related to it while changing matt sensor.

The tiny connection that goes into the BST is not very sturdy if ever removed once. I had removed it when changing battery by mistake, and I started getting air bag light after a while that. As solution I made the prongs on this tiny connector widened up a bit with a flat screw driver so that it would securely attach. Also cleaned the male and female parts with contact cleaner and put it back. I had also cleaned up steering air bag connections at the same, those were my two suspicions. I don't have the light any more.

If the tech was following repair instructions, he/she could have disconnected both the B+ and B- terminals at the battery due to working on the MRS system. Then this would be a dealer issue. However, in most cases, most techs will not pull the B+ terminal.

You are correct in the fact that it does not take much to disconnect the connector at the SBK. That's why I wonder if the OP had at one point, replaced the battery or had it out for some reason.

[rusty_g80]

Thanks for your replies. To answer X_DRIVE's question. No I have not replaced the battery in this car. I have disconnected the negative terminal when I replaced the starter about 9 months ago. Since the mat sensor change I have air bag light that comes on and if I clear it with button on left stalk it comes back after few seconds. This was not the case before mat sensor replacement. I would get the airbag light but once I clear it with left stalk button it would not appear until I restart the car.

[rusty_g80]

Have a question for people who have done this recall. Is it typical that the dealer would update the firmware in the car? My iDrive looks totally different now.

[ctuna]

I just had it done they redid my software
Don't know if they updated it or not but
I redid my coding for Window's up and No Ac with auto yesterday
as it was wiped out.
They put a small scratch on my wood trim but the leather is OK.
But I don't have idrive.
If it was working before it went in it should be on them to fix anything.
If they coded they shouldn't have had to mess with the battery though.
Coding would have reset the Seat Disconnect error.

[rusty_g80]

Update: I checked the battery terminals and the negative was loose. Fields BMW in Northfield must've employed a 3 year old girl who tightened the terminals in my car. I called the dealership back and spoke to SA (Ed) who said he will talk to technician that serviced my car and call me back. That was a week ago. I called him back the next day and left him a message, but he still has not called me back. Yesterday I just scanned the codes myself and it did show 93B2, so I reset it and the annoying air bag light went away. Dealership wanted $150 diagnostic fee to "diagnose" the issue that they caused and failed to correct. If I would've agreed to that diagnostic fee I have a feeling they would have tried to sell me a new BST cable and terminal for $1000. This was my first time bringing the car to Fields BMW because they are a lot closer than the dealer I usually go to. I will never go back there, my cousin had crappy experience there too, but for some reason I trusted Yelp reviews over my cousin's advice. Never again!

[ctuna]

This is why I would almost would rather do it all myself.
This is not limited to BMW or dealers there is a lot of F ups going on an shops that do shot gunning as there normal approach to repair these
days and its at your expense. I wish I had a garage with a lift.

[rusty_g80]

I agree with you. I wish I had garage with lift too, would make life a lot easier. Typically I fix my own cars, but since this was a recall I took it to the closest dealer.