A few weeks ago, my car exhibited classic steering angle sensor (SZL) failure symptoms - at the first instance of turning the steering wheel after starting the car, I'd get errors indicating falts with the DSC and the FTM. I'd read about this fix My $0.02 Steering Angle Sensor Fix - BMW 3-Series (E90 E92) Forum - E90Post.com a while back, and decided to try some aspects of it before giving my car up to a mechanic for a day or so.
Specifically, I pulled the steering angle sensor, opened it up, and cleaned the top side of the optical disk with glasses cleaning solution and a lint-free, super fine weave, microfiber glasses cleaning cloth. One of the posts recommended isopropyl alcohol, which I did not use because alcohol can craze some types of plastic and the optical disk is plastic. The glasses cleaning solution said it was safe for plastic lenses.
There was, in fact, a nasty brown film on the disk. I thought about cleaning the bottom side of the disk (the side with the pattern deposited on it), but I was worried about damaging the pattern, so I didn't. I also unscrewed the clear block that transmits light from the LED (it needs a tiny, maybe T-8 Torx driver). It was a bit yellowed (not crystal clear looking), and the cleaning didn't seem to change that.
I did not try to reflow any of the solder connections.
I put it all back together and drove it around on and off Sunday and to work this morning. I've not got the error again. I'm not saying that it was the cleaning that fixed it. It could have been that I'd had a loose connector. However, whatever I did seemed to have fixed it.
Some things to know:
Therefore, you can order a new one. If my issues come back, I might do that.
Specifically, I pulled the steering angle sensor, opened it up, and cleaned the top side of the optical disk with glasses cleaning solution and a lint-free, super fine weave, microfiber glasses cleaning cloth. One of the posts recommended isopropyl alcohol, which I did not use because alcohol can craze some types of plastic and the optical disk is plastic. The glasses cleaning solution said it was safe for plastic lenses.
There was, in fact, a nasty brown film on the disk. I thought about cleaning the bottom side of the disk (the side with the pattern deposited on it), but I was worried about damaging the pattern, so I didn't. I also unscrewed the clear block that transmits light from the LED (it needs a tiny, maybe T-8 Torx driver). It was a bit yellowed (not crystal clear looking), and the cleaning didn't seem to change that.
I did not try to reflow any of the solder connections.
I put it all back together and drove it around on and off Sunday and to work this morning. I've not got the error again. I'm not saying that it was the cleaning that fixed it. It could have been that I'd had a loose connector. However, whatever I did seemed to have fixed it.
Some things to know:
- The DIY linked above is for an e90. Our e60s are a bit different. The steering angle sensor looks the same and is in the same place, but getting to it is a little different. If you're mechanically inclined, it is not hard.
- You don't have to re-code the steering angle sensor to the car if you do this, because you're changing anything.
- Some early e60s had the clear block over the LED changed.
Therefore, you can order a new one. If my issues come back, I might do that.
