Faulty EPS steering with three warning lights

beatmania · 08-25-2014, 09:31 AM

Hello all! My car is a 2008 E85 3.0 si.

Recently, once in a while, three warning lights (Brake, DSC, EPS, Tire pressure) will light on at the same time, during driving, or at idle. The power of the steering assistance does not feel different. But however the steering wheel will not return to center position when exiting a corner. It will keep driving to the direction of any steering input.

The warning lights did go off, after a quick restart of the car. When the light is off, the steering feels back to normal.

One day, the three warning lights keeps light on and cannot be put off with restarting. When I go to my independent garage, the diagnosis computer reads "Error in EPS steering angle". They did perform an action called "EPS angle calibration" on the computer. The lights did go off after the calibration. Sadly, the warning lights came back again, after 500km of driving.

Before I change any hardware on the car:
1) What could possibly be wrong on my car?
2) If it's the EPS steering angle sensor that failed, is it difficult and pricey to replace it?

Any input is much appreciated. Thanks!

gas-can · 08-25-2014, 09:47 AM

Did you get an alignment done recently? If you did, the steering angle home needs to be reset -otherwise some strange stuff can happen, especially with the traction control. -edit- sorry just noticed your garage already did this.

Otherwise, if this really is a hardware failure, take a look at this document - especially the part on steering sensor/workings.

http://www.bmwclub.lv/files/06_E85_C...namics.001.pdf

I'm not sure how hard/expensive this job is- perhaps someone else can give some data on that part.

edit- the return to home of the steering wheel requires the control module to know the current position of the steering wheel - this is determined by the angle sensor so it definitely appears to be the culprit. This is probably some kind of optical sensor with a shutter wheel system mounted in the steering wheel. As the wheel turns, the optical beam gets cut off/on and the board probably reads the pulses to track the position. If you are mechanically inclined, I would open the steering wheel up and see if there any broken tabs/ stuff on the sensor. It might be as simple as a cleanup of the assembly and or gluing back a broken shutter piece... Just be careful if you need to pull the airbag...

-gc

Jstic · 08-25-2014, 10:44 AM

As stated by gas-can, you need to have your steering angle sensor calibrated or recalibrated. Independent garages often times do not have the necessary hardware/software to accomplish this correctly.

My advice is to bring it to a BMW dealer and have them pull the codes and then calibrate the SAS correctly with BMW equipment and software.

I replaced the SAS in my car as I had similar trifecta of lights. My DSC controller was getting NO signal from the SAS as it had gone bad. The dealer wanted $1400 to replace the SAS. I bought a used one online for $67 and did it myself. The dealer will pull the entire steering column to replace the SAS, as per the BMW manual, but it is not necessary and adds about $1,000 in labor to the job.

08-25-2014, 09:31 AM	#1
beatmania New Member 1 Rep 7 Posts Drives: 2011 E90 325 / 2008 Z4 3.0si Join Date: Aug 2012 Location: Beijing, China iTrader: (0)	Faulty EPS steering with three warning lights Hello all! My car is a 2008 E85 3.0 si. Recently, once in a while, three warning lights (Brake, DSC, EPS, Tire pressure) will light on at the same time, during driving, or at idle. The power of the steering assistance does not feel different. But however the steering wheel will not return to center position when exiting a corner. It will keep driving to the direction of any steering input. The warning lights did go off, after a quick restart of the car. When the light is off, the steering feels back to normal. One day, the three warning lights keeps light on and cannot be put off with restarting. When I go to my independent garage, the diagnosis computer reads "Error in EPS steering angle". They did perform an action called "EPS angle calibration" on the computer. The lights did go off after the calibration. Sadly, the warning lights came back again, after 500km of driving. Before I change any hardware on the car: 1) What could possibly be wrong on my car? 2) If it's the EPS steering angle sensor that failed, is it difficult and pricey to replace it? Any input is much appreciated. Thanks!
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08-25-2014, 09:47 AM	#2
gas-can Second Lieutenant 25 Rep 204 Posts Drives: 2006 3.0i Roadster Join Date: Oct 2012 Location: USA iTrader: (0)	Did you get an alignment done recently? If you did, the steering angle home needs to be reset -otherwise some strange stuff can happen, especially with the traction control. -edit- sorry just noticed your garage already did this. Otherwise, if this really is a hardware failure, take a look at this document - especially the part on steering sensor/workings. http://www.bmwclub.lv/files/06_E85_C...namics.001.pdf I'm not sure how hard/expensive this job is- perhaps someone else can give some data on that part. edit- the return to home of the steering wheel requires the control module to know the current position of the steering wheel - this is determined by the angle sensor so it definitely appears to be the culprit. This is probably some kind of optical sensor with a shutter wheel system mounted in the steering wheel. As the wheel turns, the optical beam gets cut off/on and the board probably reads the pulses to track the position. If you are mechanically inclined, I would open the steering wheel up and see if there any broken tabs/ stuff on the sensor. It might be as simple as a cleanup of the assembly and or gluing back a broken shutter piece... Just be careful if you need to pull the airbag... -gc Last edited by gas-can; 08-25-2014 at 10:17 AM..
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08-25-2014, 10:44 AM	#3
Jstic Private First Class 5 Rep 135 Posts Drives: 06 Z4 3.0i Join Date: Aug 2012 Location: CT iTrader: (0)	As stated by gas-can, you need to have your steering angle sensor calibrated or recalibrated. Independent garages often times do not have the necessary hardware/software to accomplish this correctly. My advice is to bring it to a BMW dealer and have them pull the codes and then calibrate the SAS correctly with BMW equipment and software. I replaced the SAS in my car as I had similar trifecta of lights. My DSC controller was getting NO signal from the SAS as it had gone bad. The dealer wanted $1400 to replace the SAS. I bought a used one online for $67 and did it myself. The dealer will pull the entire steering column to replace the SAS, as per the BMW manual, but it is not necessary and adds about $1,000 in labor to the job.
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