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Discussion Starter #1
I just acquired a 2004 C320 Wagon with 170k miles. The PO said that the car needs to have the valve body replaced as the car goes in to ‘limp home mode’ after driving 20+ miles. Where is a good place to get a used body? I’ve seen a few on EBay but wonder who you guys recommend. Also do I need to get a specific one or will any for a W203 722.6 trans work.

Thabks
 

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I just acquired a 2004 C320 Wagon with 170k miles. The PO said that the car needs to have the valve body replaced as the car goes in to ‘limp home mode’ after driving 20+ miles. Where is a good place to get a used body? I’ve seen a few on EBay but wonder who you guys recommend. Also do I need to get a specific one or will any for a W203 722.6 trans work.

Thabks
That sounds more like a conductor plate issue. Have you read error codes from the TCM?
 

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I tried to read the codes with my scan gauge, but it kept saying Connecting I never made a connection. Not sure if my old skin gate is up to the task and may need a new code reader
 

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I tried to read the codes with my scan gauge, but it kept saying Connecting I never made a connection. Not sure if my old skin gate is up to the task and may need a new code reader
Icarsoft i980 is the cheapest scan tool I know that will communicate with the transmission computer on this car. Foxwell nt520 will do a lot more. Or find someone with xentry SDS. A generic OBD2 code reader won't talk to the transmission. Also check the ATF level. Low ATF will sometimes tigger limp home mode. Could also be ATF contamanition in the TCM.
My 02 c320 wagon had ATF in the TCM when I bought it in limp home mode. No coms with the TCM. Previous owner had the conductor plate and plug replaced. When that didn't work his mechanic told him it needs a new transmission. That when he decided to sell it for $1000.
 

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Speaking of code readers I read that after you repair a transmission issue you have to go to the dealer to have the codes cleared. Is there a reader that can also do this?

My wagon was even less than yours and the owner was spooked over the tranny issues also. The car looks awesome otherwise and I’d like to take the time to sort through any issues.
 

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Speaking of code readers I read that after you repair a transmission issue you have to go to the dealer to have the codes cleared. Is there a reader that can also do this?

My wagon was even less than yours and the owner was spooked over the tranny issues also. The car looks awesome otherwise and I’d like to take the time to sort through any issues.
i980 or nt520 can read and clear transmission codes as well as every other computer in the car. NT520 has some limited coding and diagnostic capabilities beyond the i980 which in my opinion is worth the additional cost but not stritcly necessary. i980 is cheaper than 1 diagnostic trip to the dealer.

In your situation I would try to read and clear codes from the transmission and see if they come back with more driving. If there's no coms with TCM, pull up the passenger seat carpet, open the TCM and look for an oily film.
 

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Sounds like a great place to start. Did you just clean your TCM to get it to function properly?
 

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Sounds like a great place to start. Did you just clean your TCM to get it to function properly?
Took the PCB out of it's case and washed it in isopropyl alcohol then reflowed the large solder joints where the plug meets the PCB. If you find ATF in there you'll also have to replace the plug where the wiring harness goes into the transmission. That the source of your leak.
 

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Ok so I ran the codes on the icar reader and the it read “No DTCs”. I guess this means there were no error codes stored. Perhaps the previous owner cleared the codes after the car went into limp mode.

However, the check engine light is still on. Can this reader reset that light as well
 

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Ok so I ran the codes on the icar reader and the it read “No DTCs”. I guess this means there were no error codes stored. Perhaps the previous owner cleared the codes after the car went into limp mode.

However, the check engine light is still on. Can this reader reset that light as well
Yes. Either under OBD2 or Mercedes > ME2...
 

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Ok so I ran the codes on the icar reader and the it read “No DTCs”....
However, the check engine light is still on. Can this reader reset that light as well
Were you able to go through all the subsystems that are listed under your model and not see any DTC's? I ask because as a user of the iCarSoft i980, I know that it operates rather differently than the generic OBD reader I had used before getting an i980. In particular, you have to enter into each of those subsystem categories and once there, click into the indicated lines to run the check (if you have not opted to run all in the beginning) to see the DTCs. If this is all clear and obvious to you, forgive my asking, but if not, it is better to get this sorted earlier rather than later.

Also, if the previous owner cleared the codes, the CEL would have been extinguished. If the CEL then comes back, so would the code(s), and you should see them.

If you did successfully check the TCM and it has no codes, perhaps there is a code, or codes, under other categories that are triggering the CEL.
 

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Discussion Starter #12
Ok so I ran the diagnostics again and got a few codes
p2315
P2034
P2050
P2052
P2055
P201A

Whoa, now I don’t even know where to begin. Also, none of these seem related to the transmission.
 

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In looking further the P201A code can cause limp mode. This makes sense and all codes seem related to misfiring. Where to begin, plugs & wires?
 

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Glad you discovered codes. In the DTC lists I have on hand (these are probably edited to be specific for a given model), I can only find the P2315, which is a misfire on Cyl 6 (The control line to the ignition coil of cylinder 6 has a short circuit to ground).

If you have misfires, certainly the plugs and the cables are worth checking. If your car is like mine (2007 C350), there will be a coil pack that is integrated into the cable, and sits where the boot comes through the valve cover. I don't know what the ultimate reliability of the MB coil packs is, but I do know in other makes, they can fail with age, and these cars are getting on.

But first off, if you don't know the service history of this car, the plugs might be very old, long past their replacement date/mileage, and it would be prudent to replace them. Pulling them will also allow you to check for fouling on Cyl 6, to confirm if a problem is there or not. As for the coil packs, if you are able to swap the one on Cyl 6 with another (I don't know if the cable lengths allow you to do that), you might be able to verify it as defective or not.

Hopefully someone else with knowledge of your specific model, or simply greater knowledge and experience than me, will provide more and better advice.
 
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