528i RANDOMLY goes into NEUTRAL 4209A4 CODE
 

I tried searching Google and other forums about this code. Just not a lot of info out there.

2011 528i with over 200k miles.
Randomly shifts into neutral, drivetrain malfunction pops up on the dash and Check Engine light flashes. I am able to nudge the gear selector back to drive and car drives fine(until it happens again). Mostly will do it on the highway. Wont do it on short drives. Even after replacing the mechatronics sleeve and doing a fluid change the car is still randomly shifting into neutral. Had my mechanic pull the Trans codes and got Intermittent 4209A4- Transmission Temperature System. HOTMODE 3 Excess temperature with possible damage to transmission coolant line detected.

On the little info i was able to pull up...it sounds like it could be a problem with the mechatronics unit itself or the wiring that goes to the unit? I want to repair/replace the correct part.

Anyone have any info or experience with code??
https://cimg9.ibsrv.net/gimg/5series...a00e255086.jpg

What does your mechanic say, or does he not work on bimmers?

My mechanic is a "Sophomore" at best when it comes to BMW'S. He's been working on them for about 5 years. By this not being a common problem, he hasn't run across this issue before.

You're going to have to look at your EGS harness. That's what you're issue is. If you can't repair it then replace it. Do a service on the transmission while you're at it.

part# 12537598306

Seanjordan20 thanks for your insight. What makes you lean towards the egs harness versus the mechatronics unit??

Because there is a TSB for your very issue. If you had ISTA you could verify it or just simply look at it for damage. The mech wouldn't be my first thought anyway unless you know something I don't.

Inspect the EGS harness first, and if all appears well, then look elsewhere.

This week i finally got the egs harness installed using the part number 12537598306. Unfortunately that did not fix the issue of the car going into neutral.

How can INPA or ISTA help me identify the problem?? What am i looking for when using this software??

Did you do a service on the transmission? You can do a test plan to see what is causing the issue ISTA which will help you narrow it down. I don't know why I didn't post the TSB to make sure you followed the instructions

If you can post the TSB that would be very helpful. I saw a TSB about the 4209a4 code with a picture of the area that usually causes issues. Since i replaced the entire harness, im not sure exactly what to look for??

Yes, a full transmission service was the first thing i tried when i got the car. Replaced, fluid, pan/filter and mechatronics sleeve.