By YOUCANIC on Apr 13, 2019
BMW steering switch unit and steering angle sensor may fail. BMW Steering Switch Unit (also referred to as SZL, center steering column switch, and switch unit in the steering column) is a unit mounted on BMW steering column where various switches including a wiper, turn signal, cruise control mounted.
Steering angle sensor is integrated in the SZL unit. SZL and steering angle sensor can fail on any BMW causing any of the switches to stop working or trigger various warning lights. When steering angle sensor fails it triggers warning lights, most often the DSC lights which can come on randomly or as you start to drive.
When the SZL module or steering angle sensor fails the car will drive fine but you may not have traction control, stability control enabled or functioning switches. This problem has affected many BMW models including 1, 3, 5, 7, X1, X3, X5 etc.
The SZL module is mounted behind the steering wheel.
A failed steering angle sensor which is known to fail frequently and trigger warning messages plus Brake, DSC and ABS lights.
Replacing the SZL module can be very expensive ranging from $800 to $1500. The great news is that there may be a possible inexpensive fix for this problem.
You can even perform yourself. If you have been quoted hundreds of dollars for SZL replacement, because ABS, DSC, traction control lights are on due to failed steering angle sensor, you should first try cleaning the steering angle sensor as instructed below.
Cleaning the steering angle sensor is easy and in most cases fixes problems related to warning lights on the dash.
Note that BMW dealerships will not clean the steering angle sensor. BMW dealers will only replace the SZL unit or repair if there is a Technical Service Bulletin issued by BMW. If you have determined that steering angle sensor is the culprit, we will show you how to remove the SZL, open up the steering angle sensor and clean it.
If cleaning the steering angle sensor fails, you can still save money by replacing the SZL unit yourself. The good news is that you can easily replace the SZL module and let the BMW dealer or Bimmer auto repair shop code it for your for around $80-$120.
Coding an SZL takes less than one hour. Ask your BMW dealer or mechanic to carry out SZL coding, steering angle sensor adjustment system function and calibration.
Replacing the SZL yourself is a lot cheaper than having an auto repair shop or dealer replace it. Replacing the SZL module is so easy you can change it on your driveway. Just don't forget to code the SZL module to match the steering wheel features of your BMW.
New BMWs require that you also write the VIN into the SZL to match that of your BMW. Instructions on how to change BMW SZL module are provided below.
The optical sensor or potentiometer in the steering angle sensor (which is mounted on the SZL) can cause failure of Active Steering, DSC (Dynamic Stability Control), ARS (Active Roll Stabilization), AHL (Adaptive Headlights), ACC (Active Cruise Control) and the automatic turn signal reset function.
The symptoms caused by a defective SZL are different than a faulty steering angle sensor. A steering angle sensor optical sensor in the SZL can fail and trigger various warning lights. If the SZL unit is defective any of the steering column switches may stop working. Knowing which component is defective is important.
The following symptoms are only a guideline. You must read fault codes to properly diagnose a BMW.
If the SZL module fails on your BMW you may experience any of the following problems. Typically the problem starts with a random warning message on the instrument cluster which may go away and come back again randomly.
If you have any of these problems you should try cleaning the steering angle sensor first.
If you have any of the following the culprit is usually the SZL module or the switch itself and requires replacement of the component.
What you will need
Disconnect the battery and wait five minutes before you start working on airbags and SZL module.
Watch video on how to perform this step.
Remove airbag from the steering wheel. Use the access holes on the side of the steering wheel to release the airbag spring.
Disconnect airbag wires from the steering wheel.
Watch video on how to remove airbag on BMW 5-series E60.
Remove the bolt that secures the steering wheel to the steering column. You will need a breaker bar to get this bolt loose. Rember to counter-hold the steering wheel.
Watch video on how to remove BMW steering wheel.
Remove clock spring from the SZL module. Remove bolts that secure the clock spring to the SZL module / steering switch unit.
Watch video on how to perform this step.
Remove wiper, turn signal, and cruise control switches if necessary. They are held in place with small bolts. Once the bolts are removed you simply pull out the switches.
Install SZL / switch module in reverse order.
Reconnect the battery. Star the car. Turn the steering wheel all the way to the right then all the way to the left. Do this a couple fo times.
Always clear the fault codes when you replace the SZL module on a BMW. Use a BMW specific scanner to clear codes from the SZL module.
Carry out the steering angle sensor adjustment system function and calibration.
The steering angle sensor which is integrated into the SZL module is often the culprit. The most common sign is that your traction control light/DSC along with other warning lights will come on as soon as you start to drive and turn the steering wheel.
This problem is often caused by a dirty steering angle sensor that may have gunk build on it. The good news is that it can be cleaned and in most cases, it will fix the SZL problem.
There are two types of BMW steering angle sensors. Cleaning procedure depends on the type of steering angle sensor installed on your BMW. Once you remove the SZL you will be able to tell which type is installed in your BMW. As a rough guideline, most BMW before 2007 had a potentiometer steering angle sensor. While 2007 and newer use optical sensor.
Up to around 2007, BMW used a Potentiometer to measure the resistance and calculate the steering wheel position. This steering angle sensor can be cleaned with Electronic Contact Cleaner.
The optical disc over time will build up a thin layer of dirt and oil. This layer can interfere with the optical sensor. When the laser sends light to the disk the layer will block or diffract the light beam in which case the steering wheel position can no longer be determined. Clean the steering angle sensor disk and reinstall it.
Only use lint-free cleaning cloth. You can also use eyeglass lens cleaner. Use a product similar to Meguiars Clear Plastic. Note that alcohol can cause a craze on plastic optical disks. It is better to use a product that is designed to clean discs and plastic.
Once you are done with cleaning and put everything back together start up the car and turn the steering wheel clock to clock. Restart the car and drive it a short distance and the lights should reset. If the lights remain on, read codes with a BMW scan tool. Carry out steering angle calibration and clear the codes.
The following part numbers are for reference only. Allways verify part number by removing your old SZL module or by calling the dealer. Note that part numbers will change if BMW introduced a new or upgraded steering switch unit.
3 Series E90
6131 9 253 757
BMW 3 Series (E21,E30,E36,E46,E90,E91,E92,E93): 3 models, 9 variants between 2012 and 2015.
BMW X Series (E53,E70,E71,E83): 1 models, 21 variants between 2010 and 2016.
61 31 9 368 597 / 61 31 9 330 563 / 61 31 9 261 757
F45 Active Tourer / 2' F46 Gran Tourer / X1 F48 / X1 F49 / X3 F25 / X5 F15
6 958 296, 6 965 289, 9 121 893, 6 962 448, 6 989 579, 9 110 886, 6 962 675
BMW 1 E82 E88 3 E90 E92 E93
640 650 650I 640I M6 GRAN COUPE, F10
X5 E70 X5 E70 LCI
9169071 9 123 033, 6 965 288, 9 110 885, 9 196 281, 6 962 674, 6 962 447, 6 958 295, 6 989 578, 9 121 746
BMW 1 E82 E88 X6 E71 3 E90 E92 E93
9121901 9 123 049, 6 965 290, 6 962 676, 9 121 901, 6 989 580, 6 962 449, 9 110 887, 6 958 297
BMW 1 E82 E88 3 E90 E92 E93
9253746 61319253746 / 61319351140 / 61319242274
Clock spring is part of the SZL module and they are usually replaced as one unit. The clock spring can be swapped but it is not a simple job.
Check the alignment on your BMW. Bad alignment can trigger DSC light warning. Many shops will perform free alignment check. Lowering the car can also trigger the DSC light. Also, check the battery on your BMW. If it is not holding a proper charge, replace it.
Yes, the procedure is simple. If you have INAP or any BMW scan tool you can even perform coding and calibration of steering angle sensor yourself.
In the steering column behind the steering wheel.
No front end alignment is only required if the steering wheel is carried properly. Always have the wheels point straight ahead before calibrating the steering angle sensor.
Typical tools used for auto repair including torx set. No special tools are required.
No. SZL and steering angle sensor need to be installed in the car then you will have to carry out the steering angle sensor adjustment system function and calibration.
Yes. DSC and wiper or other switches may not work until the SZL is programmed.