As a long-term Mercedes-Benz 7G transmission driver, I can start off this article by saying that no other classic hydraulic automatic transmission (not even the ZF 8HP) comes close to the smoothness that I experienced on numerous test drives of the 9G transmission by Mercedes.
However, the purpose of this article is not to sing praise to the amazing Mercedes-Benz 9G transmission. We’re here to talk about its problems!
If you’re buying a Mercedes with the 9G transmission, stay with us, this article can save you some precious time and nerves!
First, we are going to cover the basic specs of the 9G transmission and see what this transmission is packing, then we are going to cover the Mercedes 9G transmission problems and see what models have this transmission. So, without further ado, let’s dive into the article.
Basic Specs Of The Mercedes 9G Transmission
The Mercedes 9G is a revolutionary torque converter automatic transmission designed to maximize fuel efficiency in Mercedes models by using more gears compared to its predecessors.
It followed the famous 7G transmission which was highly praised for its performance (and certain problems, trust me I know, I own one in my W211 E-Class). But the 9G is even better since it has more gears and further refinements.
As the name suggests, the 9G features 9 gears, which allow for better fuel economy and some incredibly smooth gear shifts. The fuel savings with this transmission compared to other Mercedes transmissions are massive since you have 9 gears.
Not to mention that this transmission has a new gearing concept that implements all these nine gears with a minimal number of planetary gear sets and shift elements.
This makes the 9G transmission a lot simpler compared to other transmissions. On top of that, the 9G is very lightweight compared to older transmissions. It only weighs 95 kilograms.
It’s also able to tackle a massive amount of torque. More specifically, the 9G can handle 1,000 N-m or 738 lb-ft of torque.
With this transmission, you are able to select three different shift modes. These include the ECO mode if you want to save fuel & save the environment. Eco mode is followed by the SPORT mode, which allows you to experience this transmission in all its glory. The last mode is MANUAL, which gives you the ability to manually select gears with the paddle shifters. You can activate all these modes with a press of a button on the center console.
Overall, the 9G transmission by Mercedes is a huge leap forward compared to older designs by Benz (looking at you 7G).
And last thing to note is that Mercedes collaborated with Jatco Ltd and Jatco is producing its own 9G Tronic transmissions, which are installed in Nissan models like the Titan, Nissan Frontier, and Nissan Z.
Also, the 9G can be found in Aston Martin models. But more on the applications of this transmission later, once we get through all of its problems.
Common Mercedes 9G Transmission Problems
Common problems with the Mercedes 9G transmission include:
- Rough Shifting
- Slow Response In Cold Temperatures
- Solenoid Failure
- Valve Body Failure
- Transmission Control Module Failure
Now let’s further elaborate on the most common Mercedes 9G transmission problems. Why do we think that this is necessary?
This is really important because you will be able to differentiate a problematic transmission from a good one. So, let’s further elaborate on these issues in detail.
One of the most common issues reported with the 9G Tronic is the occurrence of rough gear shifting.
This rough shifting occurs especially in bumper-to-bumper traffic. In other words, when you are at a stop light, and you wait and slowly accelerate.
The issue happens between neutral and gear one to gear two. Meaning that the first two gears are most affected by this problem.
There was a service bulletin issued by the NHTSA for this particular problem, since a lot of people have complained about this issue.
The bulletin says that the transmission software has to be updated along with some other things (sensors etc.) that have to be properly checked and
And reportedly, this is a software bug that is creating these issues. This is why we recommend that you don’t panic and take your car to the nearest dealership to get it inspected and see if this is indeed a software problem or if there is something wrong with the transmission itself.
Slow Response In Cold Temperatures
Another problem that people complained of when it comes to the 9G automatic is the slow response in cold weather. The 9G is known not to need an additional heating element to warm the cold transmission oil when cold-starting in freezing conditions.
Still, this transmission is not particularly happy in the cold and can sometimes bog down. This is completely normal because every transmission has problems working in freezing conditions.
It is only after it properly warms up that the transmission will start to deliver good, snappy shifts.
This is why you should not be very concerned with your transmission’s performance in cold weather because it will eventually warm up and work normally.
But if the transmission does not return to normal once it warms up, you have a problem on your hands. In this situation, we advise that you visit your nearest dealership to get this problem addressed.
Sometimes it is an internal problem that often can exacerbate these issues with poor performance in cold weather.
Solenoid failures are also common with this transmission. So, what is a solenoid, and what does this component do?
Well, a solenoid is a simple electric switch. It gets the name solenoid because it has an electrical solenoid inside that activates and deactivates whenever it gets a signal.
Inside these automatic transmissions, there are a number of these solenoids attached to the valve body itself.
Each solenoid does a different task. They are controlled by the transmission control module and whenever you need a shift up or down a different solenoid is turned on or off, which controls the flow of the transmission fluid to the places where it’s needed to lubricate the moving internal components of the engine.
Everything happens in fractions of a second and after a lot of miles, these solenoids can start to malfunction or completely fail at some point.
In these situations, you might find trouble shifting, you can also get a check engine light and even limp mode.
The important thing is to visit your nearest Mercedes-Benz shop to get this component replaced because you cannot drive like this with such problems.
Valve Body Failure
Valve body failures are also common on these transmissions. So, what is a valve body and what does it do?
The valve body is a maze-like structure that is mounted on the bottom of the transmission. This valve body is basically doing all the hard work with the solenoids in order for your transmission to shift properly. Consider like the brain of the transmission.
Sometimes these components can fail internally, and you have nothing else to do than replace them. A new unit is much cheaper than repairing the old one.
A new valve body will cost you around $1,050, or you can find a used one on eBay or a similar website for half the price.
Common symptoms associated with this problem are transmission slips, trouble shifting in a lower gear, RPM increases when up shifting, slow down shifting, up shifting and down shifting on its own.
There will also be the check engine light and trouble codes concerning this problem.
Transmission Control Module Failure
The last problem on our list is the failure of the control module. And believe it or not, this unit can also fail and cause problems with your 9G transmission.
For those who don’t know, this is the computer that regulates the transmission. This unit is very prone to failure and causing problems.
A replacement of this unit is somewhere around $1,500 only for the part, without the labor. Common symptoms associated with this unit include strange DTC codes and problems shifting.
Which Models Have The Mercedes 9G Transmission?
- 2019 – 2021 Mercedes-Benz W205 C-Class
- 2022 – Present Mercedes-Benz W205 C-Class
- 2014 – 2016 Mercedes-Benz W212 E-Class
- 2016 – Present Mercedes-Benz W213 E-Class
- 2017 – 2021 Mercedes-Benz W222 S-Class
- 2021 – Present Mercedes-Benz W223 S-Class
- 2019 – Present Mercedes-Benz W447 V-Class
- 2015 – 2022 Mercedes-Benz X253 GLC-Class
- 2022 – Present Mercedes-Benz X254 GLC-Class
- 2016 – 2019 Mercedes-Benz W166 GLE-Class
- 2020 – Present Mercedes-Benz W167 GLE-Class
- 2017 – 2019 Mercedes-Benz X166 GLS-Class
- 2020 – Present Mercedes-Benz X167 GLS-Class
- 2015 – 2020 Mercedes-Benz R172 SLC-Class
- 2022 – Present Mercedes-Benz R232 AMG SL-Class
- 2020 – Present Nissan Titan
- 2020 – Present Nissan Frontier
- 2020 – Present Nissan Z
Aston Martin Models
- 2021 – Present Aston Martin DBX
- 2022 – Present Aston Martin DBX 707
What Are The Common Mercedes 9G Transmission Problems?
Common problems with this transmission include rough shifting between first and second, problems with solenoids, defective valve bodies, and bad TCM units. But overall these issues are pretty isolated. Meaning that they don’t affect all transmissions.
Is the Mercedes-Benz 9G Tronic a Good Transmission?
Yes, Mercedes-Benz 9G transmission is without a doubt a good, reliable transmission. Our hands-on experience with this transmission and our thorough internet research revealed this is a great transmission.
Is The Mercedes 9G Automatic Transmission Reliable?
The Mercedes 9G Tronic transmission is a pretty reliable option. Much more reliable than the 7G that was previously used. And most importantly this transmission is much more efficient and will save you a ton of money on fuel.