Guys...
Okay so a while back this happened and went away after a few minutes, but now its on more often than not, and will disappear. They all come/go in unison. Scan Gauge revealed nothing and I really don't notice a difference in braking/driveability. The tires are good and properly inflated. I'm assuming its either some loose, shared connection between the systems or a bad sensor as its not a permanent condition. I was planning to drive from St. Louis to Lake Geneva Area in WI this weekend for 2 concerts. Anyone have any idea what this could be, where I should start to investigate under the bonnet, or if I should take my GF's car instead? Please let me know your thoughts.

 

Check the ABS/speed sensor wire on the front passenger wheel well side. I had a similar problem because of a frayed wire. Got the sensor replaced and all is fine.

 

Definately a Wheel speed sensor. It could be any of the 4 wheels. Your two choices to track it down are finding a mechanic with a code reader that can read MINI ABS system codes, or getting under the car and finding the problem yourself. Before you actually replace any sensors, try and clean the plugs/wires as general dirty and gunk buildup can cause them to lose signal.

Also, Search for "Trifecta" and you should get a return on more of these threads.

 

Thanks a ton for the prompt, post-midnight responses. Time is running short on this. Searching "TRIFECTA" was a huge help, so thanks a lot for that suggestion (my search yielded results all over the map). That all said, there are still a couple inquiries... I think I know what I'm looking for now, but I'm yet to find any connection point and plug to examine. If anyone can better explain what it looks like and/or where it is, you may have my first born. More importantly, I understand - having read some posts the search turned up - that the affected wheel will not have ABS active on it as a result of the error code/issue/what have you. Aside from that detail, does anyone see any danger to car and/or driver in logging between 1000 and 1200 miles on it this weekend?

Finally, Agarwaen, you referred to error codes. I have a scan gauge that has revealed nothing on this matter. I guess I figured the thing only ran engine-related codes. Does anyone know if that's correct? I assume I need a different tool, or is it a BMW-Specific diagnostic tool?

 

Definitely a wheel sensor

 

Need a BMW specific tool to read ABS codes - normal scan tools will not do this. Most car brands require a special reader to read ABS codes.

 

When I was having wheel speed sensor issues last winter, my mechanic was able to read the codes using a Solus Pro scanner -- a nice professional-grade piece of kit -- but I'm sure anything comparable would work.

 

ej, were was the wire frayed? Is there a "weak" point in particular?

 

The sensor wire was frayed near the wheel connection end. Looks like it was rubbing against something which caused the plastic sheathing to expose the bare copper wires. This was causing the sensor to intermittently transmit the data to the ECU.

 

+1

 

When I looked at mine a few days ago, I didn't see any damage to the wire. I did have a lot of trouble getting out the bolt that holds the sensor in (on both sides of the car.) I thought they were going to break off!

Now that the weather has been dry, my lights are off. That and how much rust was on those bolts, I am guess when I get the sensor out (it is stuck) I will probably find a lot of corrosion.

 

I will put money on it that your left front wheel speed sensor is faulty.

 

By "left" do you mean drivers side? That was the bolt that was by far in worse shape than the passengers side as far as getting it out. I could feel it stretch and had to go very slow to remove. Super slow.

 

Driver's side front.

 

Try using some penetrating oil to remove it, just be careful, if it breaks, you'll need a knuckle. And make sure you are using a metric allen 5mm so you don't round out the inside.