Hey guys have a 2006 BMW M5 it has been acting very strange lately. If I let the car sit and start it and drive it all is well until my motor is fully warmed up I get a Servtronic malfunction code in the dash and the steering is heavy. Sometimes I can get away with shutting it off and starting it back up but a couple more miles down the road it comes right back. Other times I can shut it off and start it back up and it will not go away until I let the car sit, but it always does come back within most drive cycles. When I do a scan it comes up with 93C1 code servtronic hardware faulty. I assumed it was the gear converter sensor on the rack and pinion so I bought a replacement and installed it and I’m still having the same issue. Any thoughts on what this could be? I also have a brand new battery I just put in yesterday and the alternator is charging at a steady 14 to 14.5 V. I also reset the steering angle to see if that was the issue as well. No luck so far. I will list pictures of the codes I am getting but I believe the Servtronic malfunction is non related to the others.
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93C1 Servtronic hardware faulty!!
Alex06M5
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How does the rack and pinion interact with the steering angle sensor optical disc behind the steering wheel? Does turning the wheel produce an expected number of degrees turn that needs to move the rack a certain number of teeth?
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Reason I ask is that maybe the implausibility signal is tied to that feedback loop?
No it doesn't reflect the mechanical turn angle. The steering angel sensor measure the steering wheel rotation degree of 440 to the right and 440 to the left which equal to 2 turn and 1/3 from lock to lock, the wheel and tire turn 45 degree approximately in response.
I don't think the system uses the steering angle sensor to test plausibility in term of servotronic, this evaluation check doesn't exist simply because there is no fault code for it. The code in this case is hardware failure and this can be caused by electrical or power issue or failed control unit internal circuitry (KGM). In addition, there is no feed back signal from the steering hydraulic flow, servo sensor or the steering mechanical angle, the steering angle sensor signal doesn't reflect the actual mechanical turn angle. The car system (DSC) will accept steering wheel deviation during the calibration process up to certain degree. In other word, if you disconnect the steering shaft from the rack input shaft and turned the steering wheel and tried to calibrate the steering sensor the system will take it.
I don't think the system uses the steering angle sensor to test plausibility in term of servotronic, this evaluation check doesn't exist simply because there is no fault code for it. The code in this case is hardware failure and this can be caused by electrical or power issue or failed control unit internal circuitry (KGM). In addition, there is no feed back signal from the steering hydraulic flow, servo sensor or the steering mechanical angle, the steering angle sensor signal doesn't reflect the actual mechanical turn angle. The car system (DSC) will accept steering wheel deviation during the calibration process up to certain degree. In other word, if you disconnect the steering shaft from the rack input shaft and turned the steering wheel and tried to calibrate the steering sensor the system will take it.
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Totally reasonable - I was just wondering aloud when I saw this thread if there was any interplay between the steering wheel sensor disc and the rack - never had a reason to look into it myself!
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So I believe the car is all set with the steering issues last Wednesday I cleared all the codes and reset steering to 0°. have been driving it since last Wednesday I put about 350 miles on it no steering issues. I appreciate all your help I believe in my scenario I just needed to readapted servtronic sensor. Knock on wood I will let you know if anything changes.
Ps. I recently noticed some rough idle coltstart issues I will be starting a thread on if you guys care to chime in. thank you again.
Interesting if it's related, what was the steering sensor reading before the reset?. I am sure the servotronic is a speed dependent but all is possible since it was hard fault and no more fault now.
When I purchased my car the steering angle sensor was all over the place with 3 faults and DSC related fault and never trigger the servotronic, sorry but hope it is fix for you.
When I purchased my car the steering angle sensor was all over the place with 3 faults and DSC related fault and never trigger the servotronic, sorry but hope it is fix for you.
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