My airbag light on the dash came on last week and I plugged in my OBD reader. It pulled an "0B safety battery terminal" fault and won't go away no matter how many times I clear it.

The car is a 2006 Mini Cooper S.

I did some research and saw the fault related to the positive battery terminal cable that is suppose to blow apart and disconnect in the event of an airbag deployment crash.

I haven't crashed, airbags haven't deployed and the cable is intact. Terminals are clean. I'm hoping not having to replace the cable since it runs all the way from the trunk, under the car and into the engine bay. Any ideas or fixes?

 

You had the seat sensor recall performed?

 

I replaced that with a seat sensor emulator last year when I swapped swapped in a set of older mini seats. The fault codes for not having the seat emulator installed were different though than this one?

 

This happened to me yesterday. The minute I saw the code I knew it was water in the boot. In 2021, now 15 years later, the crummy foam gasket for the rear hatch handle has failed me a second time.

Opened the boot and water gushed out. Luckily my amp and subwoofer did not get wet. Water in the battery well. Removed all panels, had to tap the boot lid many times to get all the water out.

Took the opportunity to silicone the 3rd brake light cover (this happened on my GP) as well the the handle. I did not replace the foam as it was intact and just went all around the inside perimeter on top of the foam. I cleaned the boot lid exterior with brake cleaner. I only had white silicone so white it will be. It was starting to drizzle.

Using my Creader VII+ OBDII scanner I was able to reset the airbag code. Restarted the car and all good in the hood. Very handy to be able to read, erase, and monitor airbagirbag codes as well as abs issues. Have to deal with trifecta on wife's 2006 mcs as well now. Probably damaged the hub when drilling out old sensor.

Pro tip: cover the latch on the car with a piece of tape so you don't have to jump the car when you accidentally close the trunk. On the GP there is no manual release cable. Had to reconnect handle, jump the car with cables connected (didn't have to start) and used handle to reopen.

Going to do the same procedure on the wife's car before that boot gets flooded with water.

 

Rained like crazy overnight. Checked it this morning and it was still leaking. Now I'm think it's the trim below the windshield. My friend told me about the weepholes at the bottom of the trunk lid and lo and behold they were clogged up. Cleaned it out with a flat head screwdriver and some water came out. Once the weather cooperates I'll try and figure out where the water is coming from. Since I sealed the 3rd brake light cover and the handle it has to be the windshield trim (upper and/or lower), the spoiler gasket area for the GP, or the MINI logo on the lid.

Those weep holes are important though because they drain out any water outside of the car. After 16 years I guess crud built up in there and got clogged.

 

weep holes? Have a pic?

i’ve been chasing this same problem in my sons r50. Nothing worked. Still getting water in the toolbox area and bottom of trunk

We replaced the trim at the top and bottom of the window

also new third break light, trunk striping, handle gasket (new handle w gasket), rear break lights…

also checked sunroof drains, working.

 

 

I’ve noticed those. We do get some water that drips out of them. Going to double check them though.

Thank you for the pic. Let us know when you get it

 

Same problem here, 2003 MCS (no sunroof). Positive battery cable/BST airbag light. Water filling up my battery box. I have been dealing with *some* water getting in probably since I bought the car back in 2010. But it is getting worse. I am annoyed to learn that replacing third brake light, tail lights, doesn't solve the water issue. I am even more annoyed that this is such a pervasive problem that MINI never addressed. I guess they figure most people park the car in a garage. Checking weep holes is #1 priority on my list.

I am preparing to tackle the positive battery cable replacement job once I can get the car up on a lift. Once I get it installed, I think I will coat the squib with dielectric grease to try to keep the moisture at bay.

I notice that my third brake light does let water in, but it is not a lot. The three screws which hold the assembly in place clearly are not enough to form a weather-tight seal with that oddly shaped assembly. I have tried to get it to seal but failed.

My left tail light has corrosion below it, so that indicates to me that those seals are bad too. The lenses are faded so I have added incentive to replace them (so long as I get a weather-tight seal when I have done so). Not sure if that water ends up in the battery box though.

I forgot that the handle is a known source of leakage.

I need to check the weep holes...

 

It is very annoying. Esp after replacing all those parts…

im going to check weep holes and get back

 

I did not need to replace anything on the positive battery cable. I just wiped it down, blew a fan on it, and let it dry. It worked fine after that.

I will order the trim now and report back after replacing it. I might try and remove the old trim but I read the tabs break off easily upon removal so I wouldn't want to not have a spare one handy.

 

Also, regarding the taillight rust that is not due to any seal on the actual taillight. That's just a crappy design by BMW/MINI. If you take the taillight out, you will see the bottom part of that cavity has sheet metal bent over more sheet metal. It's painted and there is a "seal" there but it's garbage and basically the car rusts from the inside out.

I went all out and fixed it myself. You can see the thread here. Not for the faint of heart.

https://www.northamericanmotoring.co...ight-rust.html

 

the clips do break…we replaced all of them with the trim. Although I did remember wrong. We replaced the bottom (of window) trim. Not the top.

the top appeared to be “outside” the hatch seal. However I’m questioning that in my head now. If water gets in there it would run down the door and out of the weep holes?

 

I believe the weep holes are there because the designers expected some water penetration. The foam gasket in the boot handle is your number 1 suspect and I replaced both of those on my 2 MINIs already once now. I do believe that if they leak they will dribble down and exit at the weep holes but at some point when gunk, mud, dirt, etc. clogs those weep holes, that's when it builds up literally in the boot lid. What a terrible design.

 

Wow, that's great! I did not have such luck. A few years ago, I tried drying everything out, using a heat gun, but couldn't ever get the code to clear. I tried the jury-rigged resistor trick too on a temporary basis... but had so many problems that I could not address, that I ended up parking the car for a few years. Trying to get everything back together now...

 

Thanks for that link! Looks like I've got some homework to do.

I heard from somebody that there was a TSB on the taillight rust issue. I have been meaning to do a search to see if I can find it.

 

Checked my wife's car today. Dry now but there was some serious corrosion on the terminals.

On my gp there was water in the boot. Drilled some holes through the floor of battery box to drain. There was enough water to dribble down the driveway pretty damn far. No airbag light though.








Sprayed some battery terminal spray and had to replace on 13mm nut on the right that was way rusted out.

 

I wish I could say that those images were surprising, but sadly they were all too familiar. I have been toying with the idea of drilling a weep hole in the floor of the battery box, but since I don't want to bring road water into the box, I'll do that as a last resort if I can't solve it at the boot hatch soon.

I did a similar cleanup to my battery box. The battery hold down bolt (61-21-7-577-620) corroded badly so that when I went to remove it, even after a penetrating oil application, it sheared at the battery box floor. I bought a replacement part from Mini, drilled out the old bolt, tapped a new M6-1.0 hole, and installed the new part. I cleaned contacts with a wire brush and used dielectric grease on all the electrical contact points, because I have no experience with/never bothered to purchase battery terminal spray. Is it better?

 

I don't know if it is better or not. I just think it's meant to protect the studs while still allowing electrical conductivity. I used a dab of anti-seize on the long hold down bolt and the other side of the bracket as well. Otherwise just sprayed with the battery spray.

I drilled holes in the bottom of both Minis. The heatshield for the exhaust is right below that....so all you have to do is be careful not to drill through that. There's a gap of like 1/2" or so. At least the wife's car didn't have standing water in it (but I had drilled a hole in it previously) but also there wasn't any evidence of water penetration other than the corrosion.

 

I have now taken out the tail light assembly on each side to replace with new Valeo units. I found the sheet metal bends you were talking about. It looks to me like the sheet metal folds, which are folded from the outside in, form a dam that prevents rain water from draining down the body (i.e. holds water toward the interior), leading to the formation of rust. You are right, it's a terrible design. They might have gotten away with it if this area were actually sealed off from weather, but it's not.

In the box with the Valeo tail light was an adhesive-backed foam strip seal that was not present on the factory assembly. I don't know if they 'forgot' to install it during the build, had a parts shortage, or perhaps they later revised the design. For those wondering, the strip is 3/4" x 28-3/4" x 1/8" thick. Valeo is the OEM for the tail light assembly.

The weep hole on the hatch door was clear.

 

This is where the majority of the leaks came from. After fixing antenna third brake light both tail lights handle still had leak it came from these clips they have a gasket that goes bad. There's nine of them. Don't forget the little grommet for the wiper throw a little silicone in there. All my problems fixed but I still haven't addressed my airbag light being on. My code is OB safety battery terminal. But the BST looks fine. Starts fine runs fine. Just stupid light won't turn off.