skcj213

I hoping the good people of this website can help.

I have a 2007 C230 Sport. Twice over the last month I have had an occurrence where the transmission seems to disengage for a few seconds. Both occurrences were while at speed, not at a traffice light/stop sign. The RPM momentarily increased like the transmission had been placed into neutral. Both times after just a few seconds the issue corrected itself and the car has continued on with no issue.

I have done a bit of research on this site and others and the problem sounds a bit like the speed sensor issue. However, I have not found any referrences to the problem being a momentary issue but instead folks had to pull over and turn the car off then restart for things to reset.

What are your thoughts, does this sound like a speed sensor problem? If it is the speed sensor, is it possible that the problem will correct itself or will it get worse with more and more frequent occurrences? I bought the car as a CPO in July 2010 with 29,000 miles. Currently it has about 55,000 miles. If this is the speed sensor, what is the likelihood of getting goodwill assistance in getting it repaired? The fall/winter after purchasing the car I noticed condensation in the PS headlight and the dealer, TriStar Mercedes in Ellisville, MO, did a goodwill replacement of the headlight assembly.

Your thoughts are greatly appreciated.

Glyn M Ruck

Make sure that your fluid level is correct.

The so called speed sensor issue is in fact a problem with the conductor plate. Read codes & post.

skcj213

Thanks for the response Glyn. I have read many of your posts and value your opinion.

I am not gettin a notification of the fluid being low. To my knowledge, there is no dipstick to check fluid level. Is their some other way of checking?

I have not taken the car in to be checked out and, frankly, am not sure when I will be able to. The nearest dealership is 30 minutes away from home and I work 45 minutes in the opposite direction. And the service department isn't open on Saturday. the dealership I bought the car from is 2 hours from home.

I'm a pretty good DIYer with pretty good mechanic ability. I tend to do a lot of maintenance myself: brakes, oil (when I don't have coupon from MB), engine work that doesn't require major disassembly (although I have rebuilt small block Ford from the block up). So....if their is something I can check to help diagnose I can likely do it myself.

pcy

If your car has M272 engine, there is a trans fluid dipstick tube with a cap and RED locking pin. Look on the passenger side of engine near the firewall. Remove the air filter box/engine cover for better visibility. You can check the trans fluid level [after removing that lock pin and cap] via trans fluid dipstick. You will need to buy/borrow the dipstick.

skcj213

Thanks pcy, I will have to check when I get home tonight. Assuming the tube is there, I will have to buy the dip stick. I believe I have the only C230 in my small home town. I certainly don;t know anyone with one, definitely no one that has a dip stick.

skcj213

My car has the 722.9 7 speed transmission. From what I can find it does not have a trans tube to check the fluid level.

pcy

ohh ok. I was thinking your car has 722.6 trans.

If you have 722.9, then it gets difficult... Refill will need to be done via drain plug+adapter,

Glyn M Ruck

You can DIY a fluid check by giving it a squirt with a syringe until overflow at the correct temperature. See johnand's excellent service thread on the 722.9.

EDIT ~ Do not open the transmission drain while hot. Any speed sensor value implausible etc. will store a code.

skcj213

I'll check out the thread, thanks for pointing me in the right direction. I'm not going to do much till things warm up. It's 5° outside and my garage isn't heated.

jogger

have you checked if you have error codes stored in the computer?

skcj213

Not yet, not sure when I will be able to make it to a dealership to get the codes pulled.

skcj213

It has been a while since I updated this thread. I find it very frustrating when I search for solutions to problems and find a thread started with someone with the same issue but after receiving input from knowledgeable folks the OP never follows up to post what actually worked. I don't want to be that person.

First of all, the problem pretty much cleared up through the spring and into summer. When I had the car in for regular service un July I had the trans fluid level checked, it was good, and the codes checked, there were none.

Then a few weeks ago I had the same problem several times over a week or so. One time when on the highway with the cruise set it disengaged the cruise. As the problem occurred several times within a short period I observed a little closer, the other times if sort of caught me off guard and corrected itself quickly. It really didn't feel like a slip, it was more of a hesitation or stumble. The engine RPM didn't really change, maybe dropped slightly.

Armed with new information I went back and did a search for others with the same symptoms. I found a few postings from various sights from people having a very similar problem. The common diagnosis was that the Position Sensor in the accelerator pedal was momentarily malfunctioning. This made sense with my more recent observations as the engine just felt unresponsive when the problem was occurring.

Long story short, I replaced the Accelerator Pedal assembly last weekend and so far so good. I will report back in a few weeks to update if the problems still seems to be resolved.

Again, sorry for the long absence.

skcj213

Well, sadly, after a couple of months with no issues I had the same stutter occur again this weekend. This time it set a code and the check engine light was illuminated. I had the code pulled and it is P0730. I have done some searches an can't really find a definitive answer on the cause. The next step will be to take it in to the dealer to get the transmission codes pulled to see what the problem. I'm hopeful it is minor but bracing for a big bill.

skcj213

OK, so I have heard back from the 3 dealerships I contacted.

The first, Mercedes Benz of Marion, which is the closest at 35 miles away, gave me 4 quotes, diagnostics and reflashing the transmission - $115, Replacing the Conductor Plate - $1900, Replacing the Valve body - $2600, Replacing the Transmission - $6000. Wouldn't know what is needed until they are able to look at the car.

The second, Mercedes Benz of St. Louis, about 100 miles away and the dealership we bought the car from said they typically don't replace the just the Conductor Plate but instead do the whole Valve Body. They said they have done just the Conductor Plate in the past and a high percentage of the time the car has came back with problems and they have ended up replacing the valve body as well. They quoted $1650 to replace the Valve Body. I asked him about reflashing and he was skeptical that would resolve the issue. He said the car went 60,000 miles with no issues and doesn't see how reflashing would resolve the problem.

The last shop was Plaza Mercedes in St. Louis. They quoted $1400 + tax to replace just the conductor plate. He left a message on my voice mail and didn't offer any additional input.

At this point I am leaning toward MB of STL and getting the entire valve body replaced.

Any thoughts from the good people of MBWorld?

neurodave

From the light reading I did on that code, it could be as minimal as low/high fluid (in other words, level not correct) and also the venerable transmission plug. Might be worth checking the cheap options first before you start tearing into the trans?

skcj213

I received confirmation from the dealership this afternoon that the problem is the conductor plate. They quoted $1329 for the complete repair. Of course, I have to have the work done.

I also contacted MBUSA last week to ask if they would assist with the repair. They said they would be in contact with the dealership and would get back with me. I'm waiting on a return call.

jlr82

Just a tip, if you need other service and go to Plaza Mercedes, they will do things like reflash the TCU for free. I had my car in over the weekend for new front struts and complained about another transmission problem. They were able to replicate the problem and upgraded the TCU, problems gone. They've never charged me for looking at stuff, but I am always having some other type of service done that I'm paying for.

I've never been impressed with Mercedes-Benz of St. Louis. They are formerly TriStar Motors and every single time I call and want to talk to the service department no one is available. I leave messages and they don't call back. When I have gotten them on the phone they aren't helpful and give me very generic quotes (well it'll be about $XXX) where Plaza will tell me exactly how much down to the penny for the parts and labor.

skcj213

Thanks for the feedback jlr. I went to MB of STL because I bought the car from them when they were Tristar. They have been pretty good to me and I have had all of my service, at least what I haven't done myself, done by them. I called Plaza for a quote and they were a little bit higher.

If I buy another MB, and that is a very big if, I will check into Plaza. If I can avoid the dreaded balance shaft failure I think I should be good to go.

skcj213

I picked the car up today an received a surprise 20% discount. I had a conversation with the service manager last night that ended with him telling me there was nothing he could to reduce the cost. I told him that, although we were planning to buy a GLK next year it would now likely be something other than an MB. I am satisfied with the discount.