'06 E350 722.9 transmission "sticks" in 1st
 

Car is my wife's 2006 MB E-350 wagon, NOT 4Matic, with 52,300 miles. Transmission is the 722.9 7-speed automatic, and has been serviced (fluid and filter change) twice at dealer (25,300 miles and 49,600 miles).

The transmission performs correctly 95% of the time. However, at least 5 times in the last 4 months, the transmission seems to randomly switch itself into manual mode, and the car won't shift past 1st gear (?-I'm assuming it's 1st...). It doesn't matter if it's the first start of the day, or the fourth start after running several errands--it has done it in both instances. When it does this, pushing the shift lever to the right (which seems to be how the manual states that you "clear" the manual selection) does not cause the car to go back into automatic mode. You have to bring car to a stop, place the car in park, turn off the car, and then turn the car back on again. If you do this, the transmission shifts fine. The 1-2 and 2-1 shifts sometime seem very slightly jerky to me. However, my daily driver is a '85 300 Turbodiesel with 250k+ miles, so the E-350 feels pretty much like a spaceship to me...

Anyone had similar issues, or worked on a car that was experiencing similar symptoms? I read a post on benzworld that suggested that electronics in the valve body may be the cause, and that the valve body may need to be replaced in the 7-speed, whereas with the 5-speed transmission, a conductor plate could be changed without changing the valve body. Can anyone confirm this? I plan on getting this looked at by the dealer or an indy (Benz specialist with STAR) soon--I'd like to know as much as possible beforehand so I can minimize the extent to which I will be $crewed...

Thanks--& sorry for the long post.

Sounds a lot more like an electronic/switch/computer malfunction to me than a physical one. As "rebooting" the car is fixing it when it happens.....

With the 722.9 trans you are mostly going to go to a dealer,
as they won't sell those parts (valve body) anymore!

UPDATE
 

I thought I'd update this thread since there weren't that many threads on this issue on this board. After taking the car to the dealer, it turned out that there was indeed an electronic fault in the transmission's valve body. Total cost for repair was $2,083.64. Service writer told me he's done "quite a few of these."

Technician did say that "new" valve bodies do not fail like "original" valve bodies (all the while being very careful not to imply that MB did anything wrong with the original valve bodies). I couldn't resist pointing out that my '85 300D has 267,000 miles on it with no transmission issues and his response was "yes, and it's a shame that the realities of today's car market don't allow us to build cars like that anymore."

At any rate, the car shifts wonderfully now, and I don't have to worry about my wife trying to drive all the way back from shopping in San Antonio in first gear anymore...

Good feedback!

Sorry to hear that you had to shell out $2K on such a new car though.
Make sure to have the fluid changed every 30K miles!

Other information I gathered from my conversation with the technician:

The 5-speed automatics and 7-speed automatics of this era both suffer from electronic issues in the transmissions; the speed sensors or other components in the vale body fail so the car no longer "knows" how to shift correctly and remains in one gear. Shutting the car off and turning it on again clears the fault, but then the failure occurs again with increasing frequency until the component fails completely. On the 5-speed transmissions, there is a conductor plate that can be changed independent of the actual valve body, and if the fault is within the conductor plate, this will solve the issue. However, the 7-speed requires replacement of the actual valve body;the conductor plate cannot be replaced independently on the 7-speed. I could not get the tech to say whether he thought that fluid change intervals had any impact on this issue, other than simply stating that never changing the fluid is always a bad idea. He suggested (as mbdoc stated above) that 30K fluid/filter intervals for the transmission are what he'd do if he owned a car with either of these transmissions, or any other transmission ever put in a MB. As I had mine changed at around 25K and 50K, I would tend to think that the problem is not so much the condition of the fluid, but faulty electronic parts in the initial units.

I hope this information is helpful to other folks who have similar issues--I am not a auto tech, and have no way of knowing if what I was told is 100% accurate. This particular technician has always been honest with me.

Did you happen to glean any info as to whether the valve bodies on earlier .9s (05-07) have been improved with the newer parts as of 08-up?

Do you mean are the replacement valve bodies "updated?" If so, then yes, I understood from the tech that the replacement valve bodies are not prone to failure. They have a new (different) part number--I was told this was of some importance in indicating that updates had been made to the unit. I guess I'll find out in another 50,000 miles....

I meant more along the lines of........would the updated parts appear from the factory in a w212/w204 vs what was factory-installed in late 211/203s

Sorry for misunderstanding. I think the answer to your question is yes, but I'm not sure. I learned about the problem from searching the w211 forum over at benzworld. Maybe run a search for 'valve body' in the w212 or 203 forum on that site and see what comes up? Hope this helps...

Under certain scenarios, the 722.9 conductor plate can be replaced. It all depends on which fault codes are stored. We've been performing this repair for about a year or so. In fact, we replace far more conductor plates than valve bodies.

Unlike the 722.6 transmission, the .9 transmission control unit is integrated into the conductor plate (yes, it actually lives inside the transmission, immersed in ATF). List price at my dealer is about $350, and includes a new filter, gasket, and pan bolts. :)

You are 100% correct, and I should have been more clear in my write up that the need to replace the valve body on mine was determined by the presence of particular fault codes, and that if they had been different codes, there may have been a way around replacing the entire valve body. Reading my post now, I can see that I make it sound as though all 722.9 valve bodies will have to be replaced if they exhibit the symptoms mine did, and this is not a correct statement. Sorry for any confusion, and thanks ILUVMILS for clearing this up.