ABS, DSC, Airbag & CEL light on

[speedster77]

Hi guys,

My cousin has a 2009 128i convertible and the ABS, DSC, brake, Airbag (restraint) & CEL light are on. To give you the full story: the car was completely dead a month ago and I jump started it then drove it for an hour. About 30 minutes into the drive the ABS, DSC, brake, airbag & CEL lights came on. I did not notice any difference in performance/driving. I scanned the codes using ISTA and they are in the image attached. Basically a couple wheel speed sensor codes (front left, right, rear left), DSC codes for the same wheels, switch block for passenger seat adjustment etc. I cleared the codes and drove the car again and they all reappeared as soon as I made it down the street. I checked the voltage through the secret menu while running & it was 14.1V (so I think the alternator is fine).

Since I know the car was dead and had to be jump started I suspect it's a battery issue. My first plan of action is to replace & register the battery. I'm curious if anyone has any suggestions on what the problem could be & if there is anything else I should be doing. Thank you.

[1and1]

Not sure how many miles on it, but it looks like the ABS wheel speed sensors took a dump

[speedster77]

Originally Posted by 1and1

Not sure how many miles on it, but it looks like the ABS wheel speed sensors took a dump

All of them at the same time? 98k miles on the car.

[1and1]

Yeah, mine too.

At least yours all complained at the same time, I replaced mine across a weekend, one at a time...

[dtla1]

Just try replacing the battery first like you said. Will probably get rid of all these electrical/sensor faults.

[speedster77]

Originally Posted by dtla1

Just try replacing the battery first like you said. Will probably get rid of all these electrical/sensor faults.

Thanks, I'll do that and then if it's still there look into replacing the wheel speed sensors

[Mein11]

I had this issue with my 128i back in the day. All the lights came on at once, did some research online and found many others that experienced this. Started replacing sensors and such but couldn't get the lights to go off, finally said screw it and drove the car as is. Never had any issues, the crap traction control system being permanently off was actually nice.

Anyways, drove it like that from about 120k miles to 217k miles before I traded it in. Never had any severe issues, just annoying looking at the cluster. Sometimes they would all go off on their own, but that'd only last maybe 5 miles before coming back on.

[JimD]

My front ABS sensors both failed at a little over 100K miles. They did not fail at the same time but the second one failed less than a week after I fixed the first one. The rears have not failed. I have two replacements on a shelf so I am prepared if they do.

I did not mind how the car drove without traction control or ABS, I drove many years and miles before these systems existed, but I did not like looking at the lights. I'm starting to work on my evaporative control system after several years of check engine lights. I think it's an even more worthless system but I don't like the light and I could get other codes and assume it is just this stupid system.

My dad did not tell me many things I thought were worth remembering. But he told me when fixing a car, fix first what you know is wrong and then worry about the rest. I'd do the ABS sensors first. They are cheap and it is easy. If you still have other issues, then go after those. I don't understand why you suspect the battery. I used my original over 10 years until it would not hold a charge. Then I replaced it and told INPA of the new age of the battery. I never got any issues from the old battery. I think the system responds to voltage, not battery age. As long as the voltage is within limits, it should function normally.

When I was having ABS issues I bought a cheap ($100) device that reads BMW chasis codes. AUTOPHIX is the brand. It also monitors sensor signals. So I could check the ABS sensor signals while rolling slowly in the driveway (my 128i convertible is a manual). So I could confirm the replacement was working and the one the computer said was out was out. It also codes batteries.

[66 6]

Just chased the same issue in a 10 135. Rear left and right were dead. These fixed my speedo but lights came back on. Then coded to front sensors, replaced those, then coded to steering angle. Reset that and all good.
Use quality ATE sensors, not cheap knock off or resorting to using washers to distance the sensors, which the PO must have done trying for a cheap fix.

[1and1]

Similar to my story-

late November 2020 one rear sensor failed (and caused a minor heart attack when the dash lit up like a christmas tree...)
-replaced just the one, and within 2 miles the variance between the new and old on the rear triggered another fail for the other rear, so both rear's replaced.

Then, within two weeks, in December one of the fronts failed. I just swapped both fronts to skip the surprise of finding the other front fail when the variance is again too much for the system to deal with.

For me, no hassles with the SAS- the only time it's ever coded is when my alignment (toe in this case) was massively whacked out- caused because of me, and fixed as part of the alignment correction.