I just wanted to share my experience with you people. I have had little faith in UK "specialists" based on previous experiences but it is winter and I don't have access to a pit or a means of lifting the car up to work on it. So I decided to go to MB Nottingham.
This all started because I had a fault code for the output speed sensor. My iCarsoft device reported the fault and I could look at realtime data and see no reading from the sensor. Rang the service manager and asked to book the car in to be checked over so that we could agree the solution and also check that nothing else serious was evident as the car is not worth that much.

MB Nottingham charged me a little over £100 and despite glossing over a number of non related things like oil leaks, confirmed that the solution was to replace the Conductor plate. The symptoms I had were simply a rough pick up from a closed throttle, decelerating to a junction to pressing the pedal and going. Nothing else. I had considered getting the gearbox flushed as well, so it seemed sensible to get it all done in one go. I was quoted £1400.

I got the car back and noticed that after a run if I got back in it within a short space of time it would not go into park or reverse. Also I got ESP warning lights if I selected drive and drove off. This would clear in about 20 meters. Out came the iCarSoft reader again. Now I had all three sensors (input/turbine and output) giving faults.

Rang MB Nottingham and they said bring it in. After about half an hour the service manager comes out and said it could be anything and might involve a gearbox removal. He took no notice of the screenshots I emailed him from the reader. They seemed to think that it could be the output shaft had worn bearings and was fouling the output speed sensor. I said did you check the old part for damage before fitting the new one? Er no.

Anyway I was not happy and left. I then reasoned that I had given them every opportunity to diagnose the issue and that they had, in writing acknowledged this and certainly not given any caveats prior to commencing the work.

I then decided to review them on Google and TrustPilot. Strangely then the Managing Director phones me saying he will collect the car and get personally involved. So they collect the car and about three weeks later I get a call saying the problems are nothing to do with the replacement conductor plate. But an incorrect battery / voltage issue and problems with the CAN bus and a wheel speed sensor.

Naturally they won't entertain replacing 1 wheel speed sensor and want £900 to do all 4.

Call me a cynic but you simply can't win. None of these things were diagnosed by me or them before they got their hands on the car. Suddenly all the faults that were there after the job have vanished. Seems to me they see any opportunity to rob you.

I even got the MD say to me, "we get a lot of people giving us codes" like it's some kind of divine right to only possess a reader if you own a garage. I said it's because we don't like getting shafted as general rule.
These are the error codes AFTER the conductor plate was replaced. Before that only the output shaft speed sensor was faulty.

 

Not recommending nor do I know if this service is available to your market I provide this link to hopefully assist in diagnosing, if not already reviewed: https://circuitboardmedics.com/merce...te-tcm-repair/

 

using a cheap diagnostic scanner and a small bit of believed knowledge doesn't mean you understand things or know what to do...

the speed sensor errors are dead common on ALL 7g boxes (replacement of the electroplate is effectively a service item for any car with a 7g box) Its all related to the conductor plate failing... but the failure mode is strange, they can limp on for years will NO ill effects in drivability. Replacement at a main dealer will be costly as they will charge £700 for the part and £500 to fit it, plus fluids.

the misfire / poor running pulling away has NOTHING whatsoever to do with the electro plate inside the gear box...

the crank position sensor is probably playing up that's std too.
another very common issue can be the torque converter lock up clutch failing and that's a gearbox out job and makes the electro plate look like a simple job
and the ABS sensors are probably all dead again a normal feature of these cars

 

No one said anything about a misfire. Its a diesel wise guy. The point here is that the specialists know no more than anyone else does. Added to that I gave them an opportunity to assess the car and make sure they knew the fault. The pulling away issue is because, when hot, all 3 speed sensors in the gearbox are reading crazy values and the gearbox CU doesn't know it's **** from it's elbow
I am sure you didn't read my post. I stated clearly that the car only had an issue slowing down and then accelerating away.

 

still has both the points I mention and faulty ABS sensor issues

 

It didn't have a faulty wheel speed sensor or any fault other than the gearbox output shaft sensor originally. This is obviously a bit too complex for you to follow. So here are the steps in nice easy bites:

1. Originally I found the output speed fault with the cheap and useless iCarsoft unit you mention
2. They (MB Nottingham) found the same fault with their super expensive Star system
3. They recommended replacing the conductor plate and charged me £100 for the diagnoses. I asked them to be 100% sure that this was the issue and that there was nothing else wrong of any significance. They confirmed these points.
4. They replaced the conductor plate
5. When I got the car back I then found all three sensors in the gearbox were reading incorrectly (as shown in the cheap and useless iCarsoft device screenshots above). Also I can't select Park when the car is stationary and I couldn't select reverse.
6. They took the car back, spent 3 weeks pissing around and now it has a Wheel speed sensor fault (all the other symptoms remain)

Now you might judge me and my iCarsoft device as useless but I have done an engine and gearbox swap on a W220. Fixed an ignition fault on a Vito that everyone said was a CAN bus issue (when it was a corroded RFI antenna) and I am an electronics engineer working in laser technology and audio amplifiers.

The iCarsoft unit cannot make up codes. Further, they corresponded to the Star system exactly.

You might be happy to pay an independent Mercedes garage £1500 and get f*** all for your money but I am not.

 

A dealer can sell the electroplate for £300 but won't to joe public and you can get it fitted for £350. But not at a stealership

If you have electroplate speed sensor error and you want them to go away then you have to repair or replace it... and as it has immobiliser settings locking the part to the car (as a theft dependant part - hence why dealers won't see to individuals) you need clever software to get it to work correctly. You may have other communications issues with the rest of the car (unusual) or they fitted it badly / its faulty (not unheard of)

ABS sensor will go wrong at 7 to 9 year mark regardless of mileage or vehicle use.
Crank sensor will go wrong at 7 to 9 year mark regardless of mileage or vehicle use.
Torque converter will go wrong after 100k miles, the TC clutch playing up can cause stalling and bad low speed running and will throw errors in diagnostics

 

Gear selection issues can be related to the ISM and that's common too. But normally you get a dash warning the world will end don't turn off get on a ramp now - or the car goes in P when you turn it off and its game over

 

https://mbworld.org/forums/s-class-w...-my-story.html

 

First off, you may want to clear all error codes from the car, drive it again, and see what new ones pop up -- if you haven't done that already. If the codes weren't cleared by the dealer, you could be seeing old or very old codes along with whatever is currently wrong.

I don't see anything that would indicate issues with the wheel speed sensors... those are clearly transmission speed sensors. I've seen at least one or two of those codes on my own car, which I fixed by replacing the conductor plate. Mine would go into "limp mode" and stick in 3rd gear occasionally. If you're seeing all of those and have other transmission related problems, I'd suggest sliding under the car and checking the connector that plugs into the conductor plate. Not just checking to make sure it's plugged in and locked. If it were mine, I'd remove the plug on the outside of the transmission and make sure they actually tightened the screw (I think it's a 5 or 6 mm) in the center of the pass-thru plug. Just hand tight is fine, and you'll need a deep well socket. If they didn't tighten that, you could just have intermittent connections between the conductor plate and the rest of the car.

I've been astonished at how utterly nonsensical some shops can be when troubleshooting a car. I had a little coolant leak coming from the area of my left turbo. Shop quoted me several thousand to remove the turbo, replace all the coolant lines, replace a freeze plug, and so on. I fixed it completely and permanently with a $7 O-ring, nothing else. Just a single example... the guys running these places aren't always the sharpest knives in the drawer, if you know what I mean.

I am of the opinion that owning an older W221 like these requires one of three things:

1. A very good, knowledgeable, and trustworthy local shop with extensive W221 experience and the necessary tools (like XENTRY/DAS) to do the work
2. A very substantial maintenance reserve fund, and willingness to spend every penny of it as your local shop takes the "shotgun" approach to repairs -- just replace stuff until it works.
3. A laptop with XENTRY/DAS, a set of tools, and the ability and willingness to do your own maintenance and repairs

Unfortunately #1 seems to be a very rare thing indeed. Locally we have a dealer, and one very well regarded indy shop. The dealer has made it clear that they will take my money, but really have no interest in servicing such an old junker. The indy shop seems to be somewhere between #1 and #2, but closer to #2. Fortunately, I have had the car to each and just paid their diagnostic fee before figuring out they aren't a viable choice for repairs.

So... laptop it is. I don't particularly WANT to do all my own work on this thing, but I can, and it is what it is.

 

i had the same problem with 7s