The Definitive Guide to the Mercedes 722.9 7G-Tronic Transmission (2024)

Mercedes has a long history of designing and developing their own automatic transmissions. Where many companies reach out to dedicated transmission manufacturers, you can find Mercedes units in American and German-made vehicles. The 722.9 was the go-to in the mid-’10s and is found in nearly every Mercedes vehicle, no matter the engine. Although complex in nature, it’s fairly simple to keep after and maintain with a bit of understanding. In this guide, we’ll go over what makes the 722.9 unique, some of its most common issues, how to maintain the transmission, keep issues at bay, and even how to eke out a bit more performance.

Mercedes 722.9 Automatic Transmission Overview

The Mercedes-Benz 722.9 transmission found its way into a host of chassis bearing the three-pointed star as early as 2005 in the United States and as late as 2017. It’s a traditional automatic design, utilizing a torque converter, a valve body, and many complex hydraulics. It also features some clever tricks that make it much more advanced than its predecessors.

The German-designed and manufactured automatic transmission holds seven forward gears and two reverse gears, blending performance and fuel-economy-supporting attributes. Its operating characteristics largely depend on its integrated TCU to learn, memorize, and adjust to the driving style of its owner across its lifespan.

Major improvements from the prior 722.6 transmission include a smoother drive, increased fuel economy, and quicker acceleration, all a direct result of adding more gears to the unit and enhanced gear-selection programming and engineering.

The Mercedes-Benz 722.9 Transmission At A Glance

• Seven forward gears, two reverse gears (a snow-focused softer reverse gear and standard reverse)
• Bimodal; “S” for Sport mode (higher shift points, starts in first gear, allows for manual gear selection) “C” for Comfort (softer shift points, sets off in second gear, fully automatic). Vehicles with off-road capability add a low range. Can skip gears when downshifting to grab the most appropriate gear.
• TCU control module integrated into the valve body, decreasing wiring and complexity.
• Continuous adaptation: TCU learns driving styles to adjust shift points and mannerisms infinitely until reset.
• Aluminum bell housing, magnesium case, aluminum pump plate
• Torque converter operational in all seven forward speeds
• Two different models, distinguished by the type of fluids accepted and the style of the transmission pan
• No dipstick; fluid checked via overflow or aftermarket measuring tool.

Self-Adaptation: How Does It Work?

The TCU, or Transmission Control Unit, functions just as an engine computer would; continuously adapting shift points and power delivery to the driving style of the operator and the environment the vehicle is in.

The 722.9 uses a torque converter, four multi-disc brakes, and three multi-disc clutches for forward movement. Through those components, we see the self-adaptation of the TCU, as it continuously adjusts fluid fill times and clutch pack fluid pressures. These are altered over time by the TCU to compensate for clutch wear and alterations in assembly tolerances.

Mercedes Models & Years Equipped with 722.9

Common Mercedes 722.9 Transmission Issues

While not a flawless unit, the 722.9 will, fortunately, seldom require an entire replacement when maintained properly, save for some of the 4Matic applications. In the majority of the cases exhibiting temperamental behavior, issues are often remedied with the replacement of the valve body, solenoids, or conductor plate.

Typical failure symptoms of any of the components above are on par with the majority of automatic transmission issues. This includes:

• poor performance
• harsh shifts while the transmission is cold
• holding of second gear
• limp mode
• noticeably harsh shifts
• transmission slip
• generally unpredictable gear changes

The first step, given any of the above issues, should generally be to assess the fluid quality and level of the transmission. There are two sensors built into the 722.9 used to warn of low fluid levels, but issues can occur prior to a level low enough to induce a fault code. Simply holding too little fluid can elicit any of the above responses by your 722.9, and when caught early enough, can easily be resolved by topping things off (we will discuss proper temperatures and volumes for the 722.9 below). The longevity of parts will be increased by maintaining a sufficient level of clean fluid in your 722.9 with timely service and maintenance.

Should it be deduced that a valve body or conductor plate is the cause of the issue, you'll need the TCU's VGS code. Pull the transmission pan and assess the center-mounted control unit for the VGS code, numbered one, two, or three. VGS1 will require a replacement of both units at once, while VGS2 and VGS3 allow for replacement of the conductor plate while retaining the original valve body (though should this need replacement, the new TCU will need to be coded to the vehicle).

In the most extreme circ*mstances, the torque converter’s locking clutches can demonstrate excessive wear. This is most commonly visible in the form of excessive metal fragment accumulation inside of the pan as well as a fault code (Generally 2511 or 2783) for the inability to actuate or lock the clutches. This is one of the few times replacing the transmission clutch packs, cooler, and transmission cooler thermostat is recommended in a complete overhaul. Disassembly of the unit will be required.

In 4Matic variants, we see the distinct issue of an integrated transfer case. The same 134 ATF used in the transmission is fed through the transfer case as well and will inherently be subjected to increased heat exposure in comparison to a rear-drive unit. This also means fluid will shear faster and lose lubricity, accelerating the wear rate of both the transfer case components and transmission internals. Sticking to maintenance intervals is, therefore, a bit more pressing with these models, and should the transfer case fail, you’ll generally find it most lucrative to replace the entire 722.9 unit.

As leakage is also more prevalent on these transfer case-affixed variants (most notably from the rear seal), we do recommend periodically assessing for leaks as well as transmission fluid level; over-filling as well as under-filling will negatively affect the lifespan of your 722.9 transmission. Replacing the transmission due to fluid starvation will be expensive, but keeping an eye on fluid level and an eye out for leaks is free. Should “limp home” be triggered as a result of low fluid, top-up as soon as possible and check the level with a 722.9-specific dipstick to prevent lasting damage.

If a bearing within the transfer case assembly is deemed the cause of failure, we offer a full reseal kit as well as a bearing replacement kit to get your vehicle back on the road. This has become increasingly common on these through the years and is more often than not the origin of a 722.9 4Matic issue.

Common Mercedes 722.9 Transmission Trouble Codes

As the TCU can produce over 100 fault codes and can store up to 16 at a time, you’ll need a scanner capable of reading them when attempting to troubleshoot a fault code. As fault codes are most commonly indicative of something relating to either the valve body or the conductor plate, here are some of the most common ones between the two:

• P0717
• Input Turbine Speed Sensor Circuit No Signal
• P0718
• Input / Turbine Speed Sensor Circuit Intermittent
• P0700
• Transmission Control System TCS Malfunction
• P0748
• Pressure Control Solenoid ‘A’ Electrical
• P0778
• Pressure Control Solenoid ‘B’ Electrical
• P0798
• Pressure Control Solenoid ‘C’ Electrical
• P2716
• Pressure Control Solenoid “D” Electrical
• P2725
• Pressure Control Solenoid (E)
• P2734
• Pressure Control Solenoid ‘F’ Electrical
• P2810
• Pressure Control Solenoid ‘G’ Electrical
• P2759
• Torque Converter Clutch Pressure Solenoid Circuit Electrical
• P0717
• Input/Turbine Speed Sensor A Circuit No Signal
• U0101
• No Communication With TCM

These codes may seem daunting but can be decoded relatively easily. Any codes denoting the speed sensor as receiving an “intermittent” or “no signal” performance issue are simply referencing that the feedback from the input speed sensors on the transmission to the TCU are inconsistent or nonexistent. The sensors are integrated into the conductor plate, and replacing the entire unit will generally remedy the issue at hand, as denoted by our resident Mercedes expert Kyle Bascombe in his video comparison of the 722.6 and 722.9.

Our above solenoid codes can denote an issue with individual solenoids or with the conductor plate. Symptoms of such an issue can include a shuddering under load from the transmission, as dirt clogs the solenoid over time and hinders function. Keep in mind that unlike the earlier 722.6, the TCU is integrated into the conductor plate and is VIN-coded to your personal vehicle; a replacement will require coding by a Mercedes-Benz specialist or dealer if you decide to avoid having the original unit rebuilt, or the transmission will be inoperable.

Maintaining Your Mercedes 722.9 7G-Tronic

Before discussing the maintenance of the 722.9, it is important to distinguish that there are effectively two variants of this transmission, distinguished by their engineering as an early unit and a late unit.

Early units equipped in pre-June of 2010 models are commonly referred to as “Red Fluid” models. The later units are denominated as A89 “Blue Fluid” models. The two variants can be distinguished by the color of their fluid as well as their fill pipe (the Blue models use a green fill pipe, and the Red models use a black or white fill pipe) but can most easily be deciphered by the depth of the four dimples visible in the bottom of their transmission pan. The “Blue” models have significantly deeper ovular dimples.

Regardless of the model, the procedure for servicing your 722.9 remains essentially the same; we have a full comprehensive DIY on our YouTube channel to coach you through your own 722.9 services. We also offer service kits for both red and blue units (denoted on our website in their listing title, noted as “LATE” or “EARLY”), but be aware that the 722.9 lacks an easy fill port and will require a pump to refill. Instructions on filling procedures are available via our DIY Blog.

Service Intervals

“Blue” A89 722.9 Models: 06/21/2010 to 2015 (All vehicles MY2012 and on will be blue, 2011 will need to be checked by production date)

• Fluid Type: MB 236.15 (Blue)
• Service Interval: Every ~70,000 Miles

“Red” 722.9 Models: All 722.9 Pre-06/21/2010 (All vehicles through MY2010 will be red, 2011 will need to be checked by production date)

• Fluid Type: MB 236.14 (Red)
• Service Interval: Every ~40,000 Miles

Automatic Transmission Fluid: 9.9 L (10.5 US qt.)

Mercedes-Benz 722.9 Modifications

Performance Modifications

Several ECU tuners for Mercedes models using the 722.9 will offer a TCU tune both alongside and separately from engine mapping. While sharper shifts and held gears can certainly help your Mercedes to move faster, the accelerated wear associated with harsh shift points and quick changes should also be considered; tuning the TCU would put the clutches at increased risk of failure.

Reliability Modifications

For the 722.9, we recommend running the latest SmartMediaTriple Filter. This unit offers increased filtration capabilities to remove contaminants from your 722.9 unit, helping to bolster longevity and reliability.

On models pre-2012 (or vehicles known as “Early” models, pre-A89 variation and using red fluid), this upgraded and updated filter cannot be retrofitted without switching to the deeper transmission pan design present on the post-2012 A89 variants. We offer a retrofit kit containing everything you need to fit the new filter design onto your early 722.9 transmission.

Fluid Capacities and Torque Specifications

Fill Procedure (Also found in our 722.9 Service DIY):

• Add 5 quarts of appropriate transmission fluid for the vehicle
• Start the vehicle with the fill pump still mounted, and cycle the drive selector while keeping your foot on the brake.
• Remove the fill pump while the engine is running. If no fluid leaks out, add another half quart. If it does, allow it to self-level; once the unit stops leaking extra fluid, it is full.
• Allow the transmission fluid to reach 113 degrees Fahrenheit (or close to this, based on palpable pan temperature), and mount the drain plug back into the pan. Replace the transmission bolts and gasket as well as the fluid and filter; these are one-time-use items.

Torque Specifications:

Oil Pan Drain Plug (6mm Hex): 22 NM (16 Ft-Lbs)

Oil Pan to Transmission Housing Bolts (E10): 4 NM (3 Ft-Lbs), plus 180 Degrees (One-Time Use)

Torque Converter Drain Plug (M8): 10 NM (7 Ft-Lbs)

Torque Converter Drain Plug (M10): 15 NM (11 Ft-Lbs)

With that, you have everything you should need to know about Mercedes' incredibly popular seven-speed automatic gearbox. When it comes to servicing or parts, we can help with your 722.9 ownership there, too! Head over to our main site and shop all of the parts you'll need for proper ownership. Then, head over to our YouTube channel and the DIY Blog to check out other guides and DIYs for your Mercedes. Happy wrenching!