Thank you.

but hope your car gets fixed soon : )

 

To answer all of your questions my car is a 2020 C43 with 51600 miles. I am unsure about the transmission fluid service. I am the second owner and have done 2 services, neither of which involved transmission fluid, but it is possible the first owner did. What mileage is that done at?

I was in Individual mode with the following: Auto start/stop ON, Exhaust: Dynamic, Suspension: Sport Plus, Engine: Moderate (which allows for sailing in individual mode but not comfort, obviously), Transmission: Automatic, ESP: ON .

I have a feeling that DrMattyJK is right, I think sail mode activated inappropriately "under certain conditions" ie. the transmission could not decide which gear to grab so it didn't choose any gear. Which I think is unrelated to DrMattyJK 's issue interestingly

 

I can't remember exactly but I think transmission fluid is due in 50K or 60K miles. I would do that soon. As for finding out if the service was performed already, you need to view the service history, two ways but the most reliable is through dealership's system and the VMI (vehicle master inquiry), the second way is through carfax.

That said, try to find someone with Xentry access (doesn't have to be a dealership, some independent shops have this) and get them to reset the adaptation of the transmission (always a good idea as what it does is that it erases the previous driver's driving habits and learn yours) and/or scan deeper to see if there are codes. If MB is aware of issues like sail mode getting triggered when it isn't supposed to, they might had patched it through a software update, so your next step would be to get that independent shop to perform a software update for you.

 

Fluid and gasket for transmission is due at Service B/approx 70k miles. My dealer and Indy shop both said I’d be good to 100k. If you search here, there’s some threads about issues happening after fluid change. I’m at 68k and 81 days due for service. I’m planning to change at 70k to be safe.

What you describe sounds like it could be a software issue. Have you brought it to the dealer for any service at all? It could just need an update. Also try a TCU reset if you haven’t already.

 

Transmission fluid is not changed until 100,000KM however I changed mine at 90,000KM and my car currently has 120K KM on it and drive smooth but all I can say is this, all the C450/C43 transmission, either the 7G AMG Sport or the 9G AMGG Sport, need to go back to AMG for any issues. Since your issue is intermitted, it's harder to solve. MB will drive your car and attach their tablet that will read the transmission (they did this with my car as it slammed into 2-3 gear all the time). Anyways, they took a reading of my transmission and sent it to AMG and AMG responded and replaced my Transmission Torque sensor as that seemed to be the problem. After 1 month of back and forth, they replaced the sensor and the car stopped acting all jerky in 2-3 gearing.

Your issue seems to be different than mine and not sure what could be the problem since our transmissions are controlled my the TCM.

 

Forum member konigstiger posted the service schedule for cars sold in the MBUSA market, need to find it but it was most likely 5 years or 50K Correction: it was 6 years or 60K miles whatever comes first,

70K (just my opinion though... is pushing it for the C 43), and C 63 S models as you know is even earlier.

 

That is correct for Canada indeed. So I am guessing it was 60K miles then for MBUSA not 50K. Either way, it was one or the other I just can't remember which one.

 

So I wasn't able to find forum member konigstiger's service schedule however I found this: https://mbworld.org/forums/c450-c43-...ml#post8576478
Which was part of (I guess screenshot or snippet) of the document forum member konigstiger's service schedule document that was shared.

 

So new transmission went in. Picked up Friday. Neutral condition occurred Sunday. There is a flaw in the 9Gtronic trans for the C43.

Hard to explain and I cant reliably replicate. Very random. All I can say is that if you creep to a stop in 2nd, as you slow down, as slow as can be, it eventually needs to release 2 to go into 1. Occasionally, if the car stops at the perfect time, it releases 2 and goes into 'blank' gear on the indicator and it's in a neutral condition. Free revs, no gear. like in N. Have to put in Park then gear again to go.

Anyone with a W205 C43 (9 speed auto). Think back in stop and go traffic or something like it. Have you ever had to put in Park then Drive to go again? I've seen a few videos and mention of this. Not common, but I think it has happened to more people out there. Also, resetting the adaptations or changing the control module feels good, but it doesn't fix it. There is a ticking clock to when it'll happen again in "certain" conditions. My driving style clearly brings the worst of this car. Still shouldn't happen.

Mercedes is having me drive in S mode to see if is better. Hasn't happened yet but we'll see. I'm adding Mercedes test pilot to my CV.

 

Ugh I am so sorry to hear that, I am starting to suspect the transmission isn't what is broken, it is some module that is broken and there is an communication error. Why am I saying this? It is because there is a similar experience/incident with a forum member's C 63 S, different car but I assume the communication is similar.
https://mbworld.org/forums/c63-c63s-...it-move-4.html

 

Any update on this one?

 

Glad someone is interested!!

I’ve been instructed to run in S mode and see what happens. So far so good.

Bottom line, there is a known programming glitch with the 9 speed in the W205. C mode. Auto stop start off.

Drive any c43 and the 2-1 down shift is quite noticeable, particularly if you creep to a near crawl as you slow down. For some reason, under certain circumstances, it can get stuck in between 2 an 1. Blank gear on the display. Free reving.

I bet if you asked around, more then a few C43 owners would say that their “car did not go” once or twice and just assumed they bumped into P or N or something. My driving style or traffic pattern really exposes it. I do a lot of slow crawls in traffic.

Anyone else ever had a “car did not go” issue ever????

 

Just an update for anyone interested. Mercedes eventually was tired fixing myC43 and purchased it back. Glad they came through and made well on everything. I really have nothing bad to say about the dealership (they were great) and Mercedes corp.

The repurchase experience was interesting. Took a long time start to finish. I get the feeling a lot of cars (all brands) are purchased back with many going right back into circulation. Yikes!

 

I am still sorry to hear that you have to deal with all this, disappointing to hear they don't know how to fix it but still a good outcome (buyback being a success).

What car will you replace it with?

 

BMW m340i on order.

Not ready to go all electric. Current Merc products get the horsepower out of 4 cylinders. Not the most appealing line up. Would have gladly stayed with the W205 C43. The part where it randomly wouldn’t go kinda ruined it though.

 

Congrats on your new vehicle, seems like the natural and logical decision/choice until at least the CLE 53 starts shipping.

 

You are do lucky that you live in the USA and Car Manufactures, under Law, have to purchase a car back after many attempts since Lemons are sometimes hard to resolve and it's not the consumer's fault. In Canada this is another story as car manufactures have to agree on their own terms to purchase a car back, which they never do, but will try to fix your car even if it take a year to fix it.

It took around 6 months to sort out my car as Mercedes Canada refused to purchase it back since there is no law here in Canada to take a Lemon. It was the dealership that helped me so much that in fact they gave me my own Service manager, a direct mechanic (who would be the only one to touched my car) and recorded everything plus, the manager of the Repair Center stayed in contact with me. So much so that we are good friends now. I ended purchasing my car outright since I told myself that I will never purchase a new car again as the first run of the car since my experience is that, these cars need to go through trail and error when it comes to new tech.

Even Tesla owners had to go through this pain and now Rivian owners are feeling the pain. For our goes, AMG was involved and not Mercedes, so whatever AMG did to the programming of the transmission, Mercedes techs need to speak with AMG to resolve more problems.

I hope your next experience is better because you are in a great brand but there are things manufacture have no control over and it's a reality of tech.

 

Mercedes is in the business selling cars, not buying them back. I don't want to give the impression it was easy getting the car purchased back! Working with the dealership was key as you mentioned. Particularly the shop foreman / head mechanic. They usually love a unique problem and legitimately try to fix it. MB will dictate the repair depending on the problem. They only look at hard data like your computer and video you collect (key in my case).

My only advice is for people NOT to accept any small $ amounts as "good will". You will wave many of your legal rights. Keep your options open. Check your regional laws. I wonder if you consulted a consumer law expert in Canada you would have had a case? Regardless, WAY easier fixing or settling out of court.

 

I had the exact same issue with my 2021 GLC 43 in the thread below but no one responded unfortunately. It's weird but the problem seems to have gone away, though. At least it hasn't happened in a few months.

https://mbworld.org/forums/glc63s-gl...d-while-d.html

 

If I saw your thread I would had replied, I must had missed it so I am sorry about that, let me reply now.

 

Hello,

My wife drives a 2020 C43 and was just telling me that she's having a similar problem. We just had the car in for the 60k maintenance, which was a pretty extensive including a new battery. So far three times in the past couple of weeks she's had this experience. She stops at a light, the engine shuts off, light turns green, she tries to go, the engine starts and it just revs like it's in neutral. She has to put the car into Park, then back into Drive to get it to go. I assume she's seeing this now because the battery was getting old and so maybe the conditions were such that it never did the auto stop/start thing, but now with the new battery, it's doing it again. She normally turns it off, but sometimes she forgets. I'm going to call the dealer tomorrow and chat with them about it and see what they say.

 

This is a defect that Merc refuses to address. Low volume, complex situation for the C43. The technology is now replaced. They moved on years ago.

I complained, documented and did everything I could to address the situation. They purchased my car back.

Make a complaint to national transport regulations on a safety cause. That’s all you can do perhaps?

Loved the C43 other than this issue. Wish it could have been fixed. Happy m340i driver ever since.

 

In that case, the workaround seems to be... If don't need start stop and suspect start stop caused it, the best thing to do is to disable start/stop with a scanner or unplugging the battery sensor to prevent forgetting about pressing a button and triggering it again.

 

For those that still have the car I mean. Enjoy the other car if you noved on.

 

I have ALT-LIN unplugged which also disables start/stop. To unplug the battery sensor, it can be done this way: https://mbworld.org/forums/c-class-w...tart-stop.html

To unplug ALT-LIN: https://mbworld.org/forums/mercedes-...s-voltage.html