2007 Mercedes Benz S500 • 200,000 miles

I got it checked they said on computer showing sensor bad, they replaced the same. Still exists the same. Now tgey are saying to get the gearbox down. They are not able to diagnose and the computer check is not helping to get to the right answer.
need advice
Niaz shah
January 7, 2012.

If there is a code coming from the computer that indicates an elctrical or elctronic component problem then there is an electrical problem. That is what the OBD system does. It finds electrical faults that are out of specification and need to be replaced. If they are replaced and the part is ruined in a short period of time or immediatley. There is something making it fail. There may be a short or a bad ground that is causing it to be burnt out. There may be a mechanical aspect to the failure as well. But the place to start to see why this part keeps failing is the part and if it gives a reason for its failure or if it indicates any other information. Then the diagnosis starts at that part and goes to anything that can cause the failure the part is experiencing. It sounds like somethng electrical is causing an elcectronic sensor to fail. Looking for a short or bad gound near the part is the next step I would take but not necasarily the best or only way to go but it must be something in the same circuit as the part that keeps failing. So, have them go through the circuit that the sensor is part of. Have them axplain why they think a mechanical problem can be causing an elctrical sensor to fail repeatedly as it is possible but not probable. Looking through the circuit is probably cheaper than pulling the gearbox and it must be eliminated from the possible sources for the problem anyway. So ask them why they would go to the gearbox instead of the circuit the sensor is a part of. They are obligated to expalin and guanreantee the work they do if it is stated on the repair oredr that you signed when you brought the car in. You fuilfilled your obligation by paying for the service. Now they must fulfill their obligation as stated in their terms and conditions. Hold them to it or find another shop to take your car to.
Use this site to find reputable repair shops by typing in repair shops in the search bos. It will give you reutable shops that are, NEAR YOU. Pretty nice feature huh? It is one of the many tools that make 2carpros a unique and fantastic source of the most important tool in getting things done, Information location.
I hope it all turns out well for you and feel free to come back and ask other questions if you need to. We are always here.

Car would remain in forward drive and would not change to reverse after stopping the car unless the car would not be switched off. The code showing on dash board would shopw the car be taken to workshop in the forward gear. The car was taken to mercedes workshop told me that the magnet on the transmission shows metal chips as the oil is very old. After they did this check and computer check, the car is showing clutch slip, and the car is showing a lot of juddering and stop with no movement which was not there when the car was sent for check up to the garage. They told me that we changed the software, I had told them to only check electric and check on computer. I am at a loss as now after their check up how now the car is showing the clutch slip and does not move at all, and if it does, it does not pick up the speed and I had to drive at one constant speed back at 10 kmph, while the car was juddering and I took it back to the garage and demanded what they have done to the car and that is where they told me they have changed the software. I had asked them to change the gear oil and flush the system as they said they showede me metallic chips on the magnetic drain plug. They also said me the computer reading is showing the gear shifting slippage and probable A80 being defective. I cannot believe all this and the stae of the vehicle showing clutch slippage and not gear shifting slippage, they are recommending total transmission change. I want to know when I gave them the car I had only the computer warning and the car would not go in revrse gear unless the cae was not switcged off. The car would go to any speed and and shift into any drive gear without any clutch slip or any difficulty or noise. Iwant to know what the hell this workshop has done to the car, they have given on their job slip that they have done checkups and road test, how can that change the car, is it a possibility thay drined the oil without flushing, or is it dso with software change they have done, and I am in shock as to what they have done and what I should do

Niaz shah
Jan 21, 2012.
I want to clarify some simple facts before I move ahead.
I cannot find a S500 in the service manual. There is an S550. What is the model of your car? I do not have the manual link for the S500 if it is not a typo.
I can look at models with the same transmission as the trouble codes and symptoms will be the same, it is the configuration that I really need.
Is the car an automatic or manual transmission? I have been assuming automatic.
Is the car rear wheel drive? I have assumed so as you referred to the differential oil as being different from the transmission oil. In a front wheel drive car the transmission oil is the differential lubricant.
I am also assuming it is an automatic transmission because they tried to re-program the computer to make it work.
Also the A80 code means not much more than a part is not working correctly.
However, in regards to the symptoms, services and the things you have told me about the outcome, I can tell you this despite knowing the exact model of your car as long as it is an automatic transmission.
Your car has a lot of miles on it. Your tansmission lubricant should be chagnged every 60,000 miles. If it is not, wear and tear would get the clutch packes at around the mileage you have if not sooner. If the fluid had not been changed regularly or even if it did, the metal in the oil is not surprising. I would expect it to happen more often when the fluid is not changed though. This is definately an indication that the transmission needs repair. The fact that it does not go into reverse could be the result of clutch and metal particles clogging up ports that control shifting. This is either a solenoid or a oil circuit in the valve body. The shuddering you feel is happening when you shift or at all times? If it when you shift, the torque converter or torque converter clutch is bad. If it happens all the time, the transmission has a much worse issue that is probably a bad bearing or bushing.
I do not know if you went to a dealership or not. If you wnent to a dealership I would feel better about the fact that the transmission computer or the ECU was re-programmed. This is really tough to do without special tools and circuit flash components that would be specific to the Mercedes. Unless there was a service bulletin put out about the programming that controls the transmission, re-programming it would be risky unless the technician really knew what he was doing. But, don't let that overshadow the problem. I bring it up so you can check on the service bulletin. You can go to a delearship and the service department can tell you if there is a service bulletin in regards to the cars computer programming being updated. Sevice bulletins are available to the public upon request.

In the end, the transmission does need to be fully rebuilt. If the computer was programmed and it is not the proper firmware for the transmission or there was no update issued by Mercedes that you can find in a service bulletin, I would make sure that it is set to the programming that is supposed to be at.
If it is not the proper firmware and the transmission is rebuilt it could damage the transmkission and any warranty would be void.
I cannot say that the shop is wrong or right at this point as they are so many variables and things change really fast when a transmission ends up being in such bad shape. However, if the problem got worse after the computer program, that might have caused more problems for you.
So, I am a little skeptical of the repair shop. I would go online and maybe even Angies list or the better business bureau or even check the yellow pages for reviews on there service. If they have any complaints at all, I would take the car elsewhere. Other things to look at in a repair shop that is good are things like how clean it is kept, how modern the diagnostic tools are and the overall professionalism of the staff. Does the staff wear a uniform or blue jeans and a t-shirt? These simple things can be signs of a shop that is not run profesionaly.
I realize that you will lose the money you have invest in the car at that repair shop, but you will lose much more if they repair it and do not do it properly.
Finding a repair shop that re-flashes computers will not be easy. You will have to go to a dealership or find a place that has the equipment to do it. There is a shop that I have worked with, it was on an Acura though, that does re-flash computers. It is on-line and they may be able to re-flash the computer to its proper settings. It is called, "The Swap Shop" and can be found at; theswapwhop. Com.
You are in a situation that is really tough and you are going to have to think about the long term results. You should ask them, after looking for a service bulletin, why and how they re-programmed the computer and with what model of car did they re-flash it with. Access the shop and go with your instinct as whether to have them repair it or not. Get another opinion if you can.
At this point rebuilding the transmission is something that must be done. You must make sure that the computer has the right programming o ensure the transmission will not be damaged.
Let me know if you have any questions as I know this is complicated.
I will respond ASAP.

The car is S500 automatic transmission front wheel drive. The garage is the authorized only dealer of mercedes benz in dubai, and is fully equipped workshop, sales and service garage.
When I took the car I ha problem as I had given you the first question. There was no sign of any clutch or gear slippage.
It is after their repair and reprogramming that I am having the clutch slippage, shuddering, and not going into any speed.
Please advice as I have feeling that they have done something by virtue of which everything has changed from just not going in reverse on stoppage unless switched off, to this utter huge problem of clutch slippage ang shuddering and impossible to drive, and their confession that they reprogrammed the software. Now it does not show the warning on the dash board abd now it goes into reverse also without switching off, but they have messed it by creating this problem which I believe has to do with computer setting. I want your advice and what I have to ask the dealership to do and get my car back in good condition. I believe thay are responsible for putting my car into more problem

Niaz shah
Jan 22, 2012.
Okay, flat out ask them what they re-flashed, re-programmed, the computer with. They must have used another model that is similar that they thought would fix it. That is not something that is recommended unless Mercedes Benz has put out a service bulletin on an update to the program.

The situation is a little tough because the oil is old and had some metal on the magnetic plug. But, this can be normal. The oil should be changed every 96,560 Km or 60,000 miles. If it was not much over the mileage limit, the oil would not be the issue. It all depemds on the size of the metal chips on the plug. If they were the size of filings, that could be normal wear and tear. If they are more than a millimeter in size then there is a problem.
The other problem I have with the work done is that you asked to have the computer checked. The first thing that any techician should do is to check the trouble codes to see if there are any electrical related failures. This would have been done prior to the re-programming of the computer. So either ask what the codes were if any and then ask if they even pulled the codes before changing the computer program as there would be a fault in the computer code in some cases or other clues to lead them to re-program it. You should check what issues may come up now by pulling the trouble codes. However, the trouble codes may not be reading correctly if the computer was re-programmed incorrectly so an issue might not even show up in a scan or light up the Check Engine Light.

The problem that is most likely to have occured is a failure to properly engage the shift and torque converter clutch solenoids.
This lead to an improper engagement of shifts and this allowed for the clutches to slip. Since you have the shuddering, the torque converter clutch solenoid is almost certainly involved as it has to be engaged fully after the car has taken off from a start. Sometimes they are involved in shifts but not always. The shuddering is probably a mechanical failure in the torque converter or an internal bearing. This is a result of the improper program being used which would not send the proper voltage signal at the correct RPM and pump pressure. This is my opinion based on what you have told me.

I went to the dealership and now they are saying we did not reprogrammed but erased the
codes from the system, and on this I asked them the how come the caris now showing clutch
Slippage and shuddering and is not in the shape I had given to you. I am surprised on their answer and say that the vehicle could have had this problem as the caris showing that the gearbox is defective on computer. I do not agree to it logically thatthecar will show altogether
Different symptoms on erasing the codes. Can u please give me advice

Niaz shah
Jan 22, 2012.
Well, they should have run a code check first before they did anything to the car. They would have seen any trouble codes that would have came up then, including the gearbox clutch lipping code which I have never heard of as trouble codes are generally electrical issues, not mechanical. So, they should have seen the clucth slippage problem the first tiem you brought the car in before you had trouble and told you that the clutch was slipping and suggested the full rebiuld then. I doubt that you wnet out and casued enough damage to have started the clutch to slip. How many miles did you put on the car after picking it up and brining it back? Unless you drove it over 50 miles or more I don't see an issue like that coming up so fast and they would have seen more evidence of metal particles in the oil and have suggested further diagnosis or at least have mentioned it looked bad enough that it may need a rebiuld. When a clutch slips it burns the oil and it will look dark and smell of burnt clutch material and there wouldl be clutch material and metal in the oil to give the technician a sign that there was a serious mechanical issue at that time.
It would be interesting to drain the oil and see how bad it looks, as it was just replaced, to see how many miles you drove to get it in such bad condition. Did the problem occur immediately after leaving shop? I am assuming you took it back soon. I would wonder if they put in the correct fluid and that is another reason to have them drain it while you can see the fluid and make sure it is what is specified. Auto tranmision fluid is generally red, but can vary. Just ask to see what it is supposed to take in a new bottle to at least make sure it looks like the fluid in the transmission.
Ask them why they did not mention that there was evidence of serious issues that could require a re-build the fiorst time you brought it in. If it were that close to failing, there were signs that they should have caught.
Also, if you really remember somone telling you that the computer was reprogrammed, insist on the faact that you were told that and check your repair order and see if it is on their as further back up to your case.
It is going to be hard to make them responsible for the repair even if the fault is theres. You should also tell them you are going to call Mercedes Benz customer grievance department to file a complaint. If they do not react to that, there is a number you can call to file a complaint with Mercedes Benz. You will probably find at least a geral customer service number that can help you get the complaint line in your owners manual.
That will be the last thing you can do. I would go to another Mercedes dealer or expert repair shop specializing in Mercedes to rebiuld the transmission.

Let me know how it goes.