SZL errors 94B4 / C998 / 6EC3

[Deux_Ailes_]

Hi everyone !
After a spirited driving with a biker (v), DSC and Steering lights appeared on my dashboard and the steering wheel started to feel loose.

Running a quick scan I've got the following codes (description by BimmerLink app) :
94B4 -> SZL -> LWS error (reference track distance outside the tolerance band)
C998 -> SZL -> LWS error (Wheel tolerance adjustment <-5%: F-CAN wheel tolerance adjustment, communication with DSC)
6EC3 -> Steering angle sensor : Signal invalid, status error
D515 -> Steering wheel angle above, ID = 0c4h (FC 06).

At first I thought it was a bad reading of the steering angle, so I dismantled the LZS from the steering wheel and cleaned the optical disk which was full of plastic dirt.
Brought everything back together and the codes were still there.

I then dissasembled everything about the LZS (again) and then resoldered some components. It was pointless too.

By reading values through ISTA everything looked fine.

Maybe am I missing something ? Should I pay attention to some additional values and read them via INPA instead of ISTA ?
Or is my LZS module meant to be replaced ?

Cheers guys !

 

[B21]

Welcome does the ISTA network tree / diagram show all units communicating ..any error codes elsewhere?

How old is the car?

Maybe steering ECU failure?

 

[Deux_Ailes_]

All units does respond and have a green status unless the RPA and DSC one (RPA error is somehow triggered by the DSC errors)

It is a 09/2009 E89, one of the first models I believe.

Are there other symptoms that may lead to the steering ECU failure ? Because I still can read the steering wheel angle and there's no abnormal value as far as I can see

 

[B21]

Sadly with some of these possible ECU / module failures substitution with a known good one is sometimes the only solution…

 

[Deux_Ailes_]

Here I come with good news !

First of all : the ECU is fine. Through INPA all ECUs are green (or yellow-ish for the DSC one).
I bought an E90 2010 SZL module to determine if the error came from this part or if it could be related to the ABS sensor in the arch wheel.

After installing it, the wheel wasn't loose as it used to be when the first errors came to the dash.

With INPA I recalibrated the steering angle (standard procedure -> turning full left then full right then straight in the middle + service procedure -> I had to go trough the car operations in INPA and follow the protocol showed).

Seeing new code related to the SZL module needed to be coded, I recoded it using NCS Expert and voilà !

No codes thrown, feelings are back and the cruise control is working great.

Total cost of the operation :
50€ for the module and 20 minutes of my time to fit the new module + coding.