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W221 2008 S550
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47 Posts
Discussion Starter #1
Got another problem now this car is crazy lol.
As im driving down freeway going about 65mph i noticed the car jerk outta no where what felt like the tranny.
I got off the exit to a redlight and stopped, turned the car off and back on and seen the check engine light then continued driving but now the car has very high rpm at low speeds and isnt downshifting gears properly.
It jerks really hard when shifting from R to D or vise versa.
Code scanner brought up
Error codes:
P2725-pressure control solenoid E Electrical
U140A-unknown code
U3FFF-Unknown code
Im lost at this point please help
 

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W163 and General M Gremlin
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4,986 Posts
Perhaps these older threads may be helpful

 

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W221 2008 S550
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47 Posts
Discussion Starter #3
I appreciate that,i just ordered a set of 8 refurbished bosch solenoids for $90.00 on ebay.
Part stores wanted atleast $140.00 for a single solenoid so i figured i better get all 8 and change em all out
For the cheaper price along with new tranny filter,gasket,and 10 qrts of fluid as my mechanic recommended so hopefully that does the trick🤞
I'll post an update soon thanks for your help
 

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W221 2008 S550
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47 Posts
Discussion Starter #4
I appreciate that,i just ordered a set of 8 refurbished bosch solenoids for $90.00 on ebay.
Part stores wanted atleast $140.00 for a single solenoid so i figured i better get all 8 and change em all out
For the cheaper price along with new tranny filter,gasket,and 10 qrts of fluid as my mechanic recommended so hopefully that does the trick🤞
Its crazy because Ive had 2 W220 S classes that ive never touched the transmission on and never had any issues with what so ever!
So this got me a little skeptical i just paid 10k for this car a month ago smh..
I'll post an update soon thanks for your help
 

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W221 2008 S550
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47 Posts
Discussion Starter #5 (Edited)
Flushed the whole tranny today,old fluid was black as s**t and almost 2qrts low.
Still in limpmode but now its only showing an evap code throwing the check engine light,no more pressure cntrl sol E code P2725 like it had before :unsure:.
 

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W221 2008 S550
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47 Posts
Discussion Starter #6
Took it to Mercedes they confirmed it is the solenoids.
 

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W221 2008 S550
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47 Posts
Discussion Starter #7
So i had a private mechanic change out all 8 solenoids and car still driving the same smh.
Also while removing the valve body the mechanic pulled the conductor plate off the electrical harness exposing the circuits but was able to plug it back on.
Idk its still in limpmode
 

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Premium Member
'71 Pinto
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4,786 Posts
Assumption solenoids replaced, valve body cleaned and connected properly but problem still exists. Given old fluid condition it could be internal valve body pressure regulator valves. Sonnax offers valve kits Mercedes 722.9 Transmission but tooling is needed. Not up to this task my suggestion, consider replacing valve body.

Capture.JPG
 

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W221 2008 S550
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47 Posts
Discussion Starter #9
I helped the mechanic do the work and i personally tested each solenoid w/ a 9V battery and plugged them into the Conductor plate myself.
Now was it put together correctly? No clue but the solenoids all worked.
Im curious If the conductor plate is bad will it have any specific symptoms?
 

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W221 2008 S550
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47 Posts
Discussion Starter #10
MB called and said clutch packs are contaminated with wrong fluid and the whole tranny needs to be changed.
I put Valvoline Max life full synthetic which was given to me by O'Reilly autoparts according to the specs in their system.
They want almost $8k to replace it,im still not convinced that the whole thing is ruined i mean it still drives
 

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1997 C280
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152 Posts
I say you need to drain it and refill it with the Mercedes tranny fluid. I got cheap and got the Valvoline Max Life fluid before and had issues even though it said it would work with the MB tranny. You got to fork out the $$$ for the MB fluid. ($25 per quart.) After I did the above and got my MB mechanic to change out to the proper fluid, I had no issues.
 

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W221 2008 S550
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47 Posts
Discussion Starter #12 (Edited)
Dealer put their atf in it after telling me the tranny was ruined. Then their tech said ''its driving fine now but idk for how long''lol.
Then charge me 645.00 after diagnostic for an additional 245.00
I got in and its still on limp mode, $890.00 for MB dealer to fix absolutely nothing.
Ive been going around to get other opinions from different shops and i keep hearing you have to check and reset the TCM with a proper scanner.
I dont think Mercedes reset anything,check engine light/ABS light both on dash i thought their scanner tool would check all fault codes?
 

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W221 2008 S550
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Discussion Starter #13
UPDATE**
I went to another independent euro mechanic shop today, they plugged it to an "Autologic" diagnostic tablet and scanned for codes.
I asked why they didnt use their STAR and they told me this one is faster but would read all the codes the SDS would catch.
Alot of codes came up,more than i could count but none were related to what is actually happening with the car.
Cleared the codes and checked again only a couple codes came up:Radio through a code and parking break aswell.
Both of those seem to work fine so i thought was strange.
Check engine light went away but "ABS/ESP inoperative" still on.
They said to drive and see what happen.
I put in D, it jerks hard and drive its still in limpmode but still has power.
I get to a light,turn off,restart,and check engine light is back.
Only this time i put in D and it doesnt jerk,goes in gear smoothly but when i hit the gas its got no power.
Im talking barely moving for how hard i press the gas.
i pull over restart again,put in D,car jerks hard again but regains power in limpmode like before.
😖😖😤
 

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1997 C280
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152 Posts
You did not say if you replaced the conductor plate. If you did, the transmission control module is attached to that conductor plate and that TCM will need to be reprogrammed to your car. That maybe the issue. (MB makes it more difficult now!:()
 

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W221 2008 S550
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Discussion Starter #15
I havent replaced it yet.
Im thinking i'll try that and see what happens.
It has VGS2 marked on the plate im guessing that is the TCM?
Will have to be updated to 3? Or can i use another 2nd series like what I got?
 
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