BMW E90 Steering Angle Sensor Diagnosis

March 25, 2013 | Reply More

A regular customer brought in his 2007 BMW 328XI E90 because the “lights” were illuminated. We asked which lights. He told us that the traction control, 4×4, and brake dashboard warning lamps were all on at the same time, but that they went out after the key was turned to the “Off” position. Obviously, some troubleshooting was in order.

As Murphy’s Law would have predicted, when the car was started and driven straight into the back of the shop, none of those lights were on. Since BMWs store history codes, we concluded that a full system scan would be a logical first step. These days, the quick test is becoming a “must do” because there are so many modules connected to different networks that problems can be interrelated.

Very often, a quick test shows that some modules have issues or faults classified as “sporadic,” meaning the errors do not happen all the time. The appearance of such codes may be a warning of an upcoming fault, but are often part of normal operation, meaning these codes exist on a permanent basis and do not reflect a problem. We like to call these “ghost codes.”

Right turns only?

When checking the steering angle PID on your scan tool, make sure that the steering wheel is arrow-straight. You should see 0 degrees.

After we saved the code information, we cleared all the faults and drove the car to see if any hard codes would come back. It didn’t take long to find out that if we made hard right turns, the Dynamic Stability Control (DSC) module showed three codes that were “stored.” They were 5EBA Steering angle sensor plausibility, 94BB Steering angle sensor: internal fault, and 94B5 Steering column switching centre: internal fault. When most technicians working under the gun see these codes, they immediately condemn the steering angle sensor. This is not really such a terrible diagnosis because when a module sets an “internal fault” DTC, the usual cause is simply that, an internal fault. However, the wrong year sensor or connectivity issues can also set internal fault codes, though this is rare.

When we called the dealer and heard that he actually stocked the steering angle sensor and wouldn’t have to order it, it became apparent to us that this represented a pattern failure on E90s. The part, however, costs $525. Do you want to take a $525 gamble? For those of you who aren’t big gamblers, what we are going to cover here is how to be sure the culprit is really the steering angle sensor itself, and not some problem elsewhere in the system before you risk that considerable amount of money.

As always, basics first

As any successful technician will tell you, the first step should always be to cover the basics. Check the mechanical integrity of the vehicle. Inspect the front end for ripped bushings, look for bad control arms, and make sure different/wrong tire sizes aren’t present. Also, test the battery, look for ripple voltage

 

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Category: Steering + Suspension, the bimmer pub

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