Front stabilizer bar link disconnected, nut identification & chassis stabilization error

[mdpalmer]

Can't get under the car right now, have a part identification question for you guys and questions on resolving a chassis stabilization error I got while in the middle of my first autocross recently (which was super fun BTW I'm hooked!).

In the middle of one of my later runs, I heard the cabin chime come on and when I lined up for next run I see a chassis error code in the dash. "Chassis function limited, continued driving possible". Video from inside car of that run you can hear it chime.



Car seemed to drive ok. When going home for the day I thought I heard some clunk from the front suspension when at a large steering angle at low speed (parking lot maneuvers). Drove home without incident.

The weekend after, when I got time I took the car out for a wash and to see if I could get a better view of the suspension, and I saw the front stabilizer bar link on the passenger side is disconnected from the upper mount. See pics.

What bothered me is that I think I know why it became disconnected. I remembered when I had my spacers and springs installed at a shop last year, the shop gave me the box the spacers came in... there was an extra nut in that box (along with my stock wheel bolts since longer bolts were installed with the spacers). I didnt think anything of it at the time. However it looks like that leftover nut was never installed back in the original spot.

I'm actually blown away it took this long for this to happen, I did one track day, a few hard canyon runs and daily beatings every time I drive the car. Been well over a year now.

Can you guys confirm based on these photos that this is the same nut that should have been installed? I will get under the car next weekend to have a look. Anything in particular I should look out for? Also attaching pics from shop manual for reference.

Also any ideas on how to deal with the error code, is this something that can be cleared with Bimmerlink?

Thanks in advance.

Sponsored

 

[Eastwood]

Yeah. That’s the sway bar nut. I can tell by the groves on the lip.

What shop did the install? Huge mistake on their part.

 

[jchadwell]

Ditto. Crazy they left it off but we are all human. I’ve done my share of really stupid things so I tend to cut people a break unless it’s a gross negligence situation. Reinstall that nut and the code should go away.

 

[FLtrackdays]

Glad you're enjoying the car & tracking her! I do a bolt check prior to each track weekend & shit still happens. You’ll need shop/place that’s more versed in tracking going forward for sure.

 

[mdpalmer]

Finally had a chance to get under car. Reinstalled the nut, car drives fine, no more noises. Chassis stabilization error still present tho. I pulled the info/error code using Bimmerlink and the following persists, even after attempting to clear it with Bimmerlink:

Vertical dynamics platform
1 error
48289A: Digital wheel acceleration sensor - front right - physical layer error

I checked the sensors and wires, one of the pieces was hanging loose and a bracket attached to the knuckle was bent. Didn't look catastrophic tho. Unplugged and replugged the sensors on the shock, no change.

After doing some searching it seems that wheel acceleration sensor problems are nothing new to BMWs... I haven't been able to find anyone report the same error I have though. "Physical layer error"... Exactly what does that mean?

Any ideas? I'm gonna check with the shop that did the spring install. I am not going to take car to dealer, I'd rather fix it myself. If that involves getting diagnostic equipment for a reasonable cost I'll go that route.

 

[Traxion]

I had that code pop after I changed out suspension. I cleared it and drove it around so that it cycled and never came back. It should be related to this sensor. Mine looks different obviously because this is aftermarket suspension but you should see this somewhere on your strut. Double check this. If its connected and clearing codes didn't work, then unplug battery to power cycle and then take it for a drive. If you aren't hitting limp mode then you can effectively ignore it otherwise.

 

[FLtrackdays]

Finally had a chance to get under car. Reinstalled the nut, car drives fine, no more noises. Chassis stabilization error still present tho. I pulled the info/error code using Bimmerlink and the following persists, even after attempting to clear it with Bimmerlink:

Vertical dynamics platform
1 error
48289A: Digital wheel acceleration sensor - front right - physical layer error

I checked the sensors and wires, one of the pieces was hanging loose and a bracket attached to the knuckle was bent. Didn't look catastrophic tho. Unplugged and replugged the sensors on the shock, no change.

After doing some searching it seems that wheel acceleration sensor problems are nothing new to BMWs... I haven't been able to find anyone report the same error I have though. "Physical layer error"... Exactly what does that mean?

Any ideas? I'm gonna check with the shop that did the spring install. I am not going to take car to dealer, I'd rather fix it myself. If that involves getting diagnostic equipment for a reasonable cost I'll go that route.

I had that code pop after I changed out suspension. I cleared it and drove it around so that it cycled and never came back. It should be related to this sensor. Mine looks different obviously because this is aftermarket suspension but you should see this somewhere on your strut. Double check this. If its connected and clearing codes didn't work, then unplug battery to power cycle and then take it for a drive. If you aren't hitting limp mode then you can effectively ignore it otherwise.

Yeah many things do tend to work themselves out with these cars if it wasn’t from something you did (such as installing new springs). Many suspension parts I’ve purchased & installed say the system may need recalibration after replacing or adjusting. Unfortunately w/out good diagnostic software, it’d be hard to know w/out working it backwards.

I have two shops that are really good with BMW software & calibration issues. Since it says that the sensor works with adaptive damping and electronic suspension control, it definitely could have happened during install. Sounds like you’ve already done a lot of the steps. Sometimes when you look these up it can mention a possible fault in the control module. Which is less likely. I use GPT-4o at work when comparing medical journal articles. So I asked it to find a solution for that code. Here’s what it came up with:

Steps to Diagnose and Fix:
1. Inspect Wiring and Connectors:
• Check for visible damage to wires and connectors leading to the sensor.
• Ensure all connections are secure and free of corrosion.
2. Replace the Sensor:
• If wiring appears intact, replacing the sensor is a logical next step. Use an OEM part to ensure compatibility.
• Follow proper installation procedures, including securing the sensor to its bracket correctly.
3. Check and Adjust Bracket Alignment:
• Straighten or replace the bent bracket to ensure proper alignment of the sensor.
4. Clear Fault Codes and Recalibrate:
• Use diagnostic software (e.g., ISTA+ or BimmerCode) to clear fault codes after repairs.
• Perform any necessary recalibration of the suspension system.
5. Test Voltage and Communication:
• Use a multimeter to verify that power is reaching the sensor and that it is sending signals back to the EDC module.
• If no signal is detected, inspect wiring further or consider replacing the cable.
6. Seek Professional Diagnostics if Needed:
• If replacing the sensor and addressing wiring issues doesn’t resolve the problem, a professional diagnostic tool like ISTA+ can provide more detailed insights into potential module faults.

Hope that helps!!

 

[razorlab]

I bet the endlink damaged the velocity sensor wire. You are lucky as it could have done WAYYY more damage. I believe that harness is around $45.

 

[FLtrackdays]

I bet the endlink damaged the velocity sensor wire. You are lucky as it could have done WAYYY more damage. I believe that harness is around $45.

That would be a nice simple fix!

 

[mdpalmer]

Closing the loop on this, the shop was more than happy to fix the issue at no cost to me. First trip in they found the issue: damage to a piece of wiring. They didn't have replacement part on hand, so they repaired the wiring and code vanished.

Put some miles on car, did an autocross event, I was so happy not to see the chassis code on the dash.

Just went back today and they swapped in a new harness and here is what the part looks like that was damaged, notice the spliced piece of wire.

I looked it up on realoem and also cross referenced the Toyota PN. Hope this helps someone.

Toyota
Adapter Cable Remote Battery Switch Front Axle
PN: 90118-WA505
https://autoparts.hendricktoyotaconcord.com/products/product/adapter-cable-rbs-fr-90118wa505

Realoem (item 10)
Adapter cable RBS front axle
BMW PN: 37106886746
https://www.realoem.com/bmw/enUS/sh...18_G29_BMW_Z4_M40i&diagId=31_1547#37106886746

Pics of repaired part:

Part diagram from realoem:

Sponsored