Brandt51 wrote Yeah, troubleshooting it sounds sort of like shooting into the dark. The dealer diagnostics might break it down a little better. But yeah, the few people with experience sorting that out prob wear a bmw tech uniform.
I’m all about changing parts until it’s figured out tho! I’d be concerned about a connector having corrosion or a broken wire, but maybe the car is newer, not so much corrosion.
Oh, If you haven’t checked before, take a look at the M5 forums. Similar car, but a whole lot more of them. So somebody there might have had this problem before.
Excellent idea re M5 forum! I’ll give that a shot.
And I wish more information were available 
I’m also thinking it could be a corroded or lose connector. Everything looks good though.
I unplugged the IBS and it takes a bit longer for the error to come back - with the sensor, I get an error within 5 minutes of driving. Without the sensor it can take 15-20 minutes of driving.
CGPT thinks it might be a loose ground - the main battery ground is perfectly secure and no corrosion. Ditto for the second battery in the chassis. I haven’t checked other grounding points but the car is pretty clean and no real corrosion.
Troubleshooting continues.
The good news is that everything works properly before the error. So I don’t think I have an actual failure. The car is very comfortable before and uncomfortable / doesn’t feel planted after the error…
Thanks for the reply.
