MyTeeOak

We recently purchased a 2006 MB R350 wagon as a runaround car. The previous owner told us that it had an issue will randomly shifting into park while driving. My wife and I have both experienced this now, where we are driving at normal city speeds (below 50 mph) and the car either shifts into park randomly and/or turns off while shifting into park. The previous owner advised that when they took the car into the dealership, the dealership wanted to charge them over $10k to replace the transmission which they felt was causing the problem. I have been searching a few forums and was thinking it could be some of the issues listed below, but I wanted to see if anyone dealt with a similar issue and how they fixed it.

1) Transmission Control Module
2) Alternator
3) Column shifter
4) Door sensor - as the vehicle automatically shift into park when a door is opened
5) Something else completely

MJ50

moved to W251 forum...

R3504Matic

may need a couple transmission fluid and filter changes. There can be particles in the solenoid that can get the solenoids stuck.
They kit is not that expensive if you want to do a rebuild of the valve body.
There are many videos on how to do it.

Then you need to have the modules reset once done.
But at least start with having the Transmission fluid changed along with the filter, pan gasket and new aluminum bolts.
Kits are sold on FCP Euro
https://www.fcpeuro.com/products/mer...em-7229erlysk1

https://www.fcpeuro.com/products/mer...on-service-kit
https://www.fcpeuro.com/products/mer...oid-2402700089

Transtar sells the kits for solenoids in valve bodies
https://www.transtar1.com/TranstarIn...ndex.html#p=20
https://www.transtar1.com/TranstarIn...index.html#p=4

Depends on your transmission type. You can go to LastVin.com and find out, put in your VIN and it should show built.

R3504Matic

Also Gary Ferraro is one of the best Trans Tech Tutorial

EastCoastMetris

Hi MyTeeOak, any luck on this issue? My 2016 Metris van is going into park at low speeds and I feared it was possible at higher speeds. What the heck happens at 50mph? Does it slam to a stop? The dealer cannot replicate my issue and the van shows no codes etc. Thank you.

R3504Matic

Changing trans fluid and filter is a big deal. Some solenoids should be maintained, It isnt that expensive to get it done. Im pretty familiar with those this issue as my BMW and Mercedes will do this if you dont change your fluid often. Valve bodies and have dirt and debris it in and it can make those solenoids get stuck.

EastCoastMetris

Hi @R3504Matic, are you referring to the issue of shifting into Neutral or Park? Or would the same issue cause both? Do you know what happens if the vehicle goes into park at 50mph? Thank you!