Is your Mercedes-Benz stuck in second gear (limp mode) and the check engine light came on? You are experiencing transmission problems. You press the gas pedal, and the engine RPMs go up to 4000 or even higher and you are limited to a max speed of about 30 MPH. The check engine light (CEL) comes on. You scan the car using an OBD-II code reader, and you get fault codes such as P0715, P0720, P0700. Diagnostic Trouble Code (DTC) P0715 is detected when TCM or ECM does not receive the proper signal from the input/turbine speed sensor.
Quick Tip If you need to get home, try turning off the car. Remove key and wait a couple of minutes then restart the car. You may be lucky and get the car out of limp mode. It is a matter of time before your Mercedes-Benz goes back into limp mode. Get your transmission problem resolved. Read on to learn how to troubleshoot and fix the most common Mercedes Benz automatic transmission problems.
Mercedes Automatic Transmission Fault Codes
Here is a list of Mercedes 5-speed and 7-speed automatic transmission related error codes.
- P0720 – Output Speed Sensor Circuit Malfunction
- P0715 – Input/Turbine Speed Sensor Circuit Malfunction (Transmission Conductor Plate or 13-pin connector issue)
- P0700 – Transmission Control System Malfunction (Generic Code telling you there is a gearbox problem)
- P 0716 P0717 P0718 – Input / Turbine Speed Sensor Circuit Malfunction / Range Performance / No Signal / Intermittent
- P0719 – Torque Converter Brake Switch Circuit Low
All these fault codes point to powertrain malfunction, typically automatic transmission problems.
- Mercedes-Benz does not shift properly
- Check Engine Light / Service Engine Light On
- Stuck in second gear / Limp Mode
- High Engine RPM
- Limited Max Speed of 30 MPH
In most cases the problem is one of the following:
|Mercedes Benz Valve Body 722.6 5 Speed Transmission|
|Defective Conductor Plate|
|Failed 13-pin connector harness, Leaks Oil, Transmission O-Ring|
Cost to fix P0715 P0720 P0700
The good news is that to repair any of the problems mentioned above you don’t need to remove the transmission from the car. You can perform the repairs with the transmission in place. The most expensive repair could cost a few hundred dollars.
The first thing that you should check is the 13-pin connector plug. This is the electrical wire harness that plugs into the valve body which is inside the transmission. It leaks oil and causes communication problems between the transmission control unit and the sensors on the valve body. This part costs less than $20 and can be found on Amazon. Follow this article on How to replace the 13 pin connector on Mercedes-Benz transmission.
If the valve body conductor plate is the problem, then you are looking to spend $150-$250 for the conductor plate. Auto repairs shops may charge between $650 – $950 depending on your location. Mercedes-Benz dealership has reported quoting between $1400-$1800 for this repair. One place where you will find reasonably priced conductor plates for Mercedes-Benz 5-Speed 722.6 and 7-speed 722.9 transmission is Amazon.
How to replace the valve body
If the 13-pin connector doesn’t fix the problem, then the next step is to replace the valve body conductor plate. Replacing the conductor plate is easy. It is mounted of top of the valve body. You will need to remove the valve body from the transmission. Transmission doesn’t need to be replaced. The valve body can be removed from underneath. Replace the conductor plate and reinstall the valve body.
The codes listed above give you a general idea of what’s wrong with the car. They are fault codes stored on the Engine Contol Unit (ECU), you get them from a generic OBD II scanner. To properly troubleshoot the transmission problem on your Mercedes-Benz, you will need a diagnostic scanner that can retrieve the fault codes from the transmission control unit (TCU). The next step is to get a hold of such an advanced diagnostic scanner, read the TCU error codes which will help you narrow down the problem with your Mercedes-Benz. If you don’t have one, there are a couple of affordable scanners that will allow you to read transmission fault codes (also abs, ets, esp and most of the systems on your Mercedes-Benz) and you can find these scanners on Amazon, see links below.
|Launch Creader Engine Transmission ABS Airbag Scanner|
|iCarsoft MB II Mercedes-Benz Diagnostic Scanner|
Both of these scanners have very similar functionality. Watch the video on the next section on how to utilize these scanners to read the transmission fault codes on your Mercedes-Benz. If you would like to read more about diagnsoitc scanners that work on Mercedes-Benz you may find this article helpful: Top 10 Best Diagnsotic Scanners for Mercedes-Benz.
Once you fix the problem such as replacing the 13-pin connector or replace the valve body, you will need a diagnostic scanner such as Mercedes-Benz Star DAS or one the scanners mentioned above to erase the fault codes and get the car out of limp mode.
How to read and erase transmission fault codes.
Use an advanced scanner to read the fault codes from the transmission control module. Fix the problem that is specific to your car then use the OBD-II scanner to erase the fault codes to get the car out of limp mode. Watch video on how to use the scaners mentioned above to read and erase the fault codes.
Depending on your troubleshooting outcome here are some articles that will help you repair the problems on your Mercedes-Benz.
|13 Pin Connector – DIY Replace Transmission Connector Adapter Plug O-rings Mercedes Benz 722.6|
|Mercedes-Benz Valve Body 722.6 NAG1 Installation|
|Check Transmission Fluid Level|
Still having Automatic Transmission Problems
If your Mercedes-Benz transmission is still acting up, there could be other reasons that can cause it to shift erratically, be stuck in second gear, limp mode, stuck in park or other problems. Read Mercedes-Benz Automatic Transmission Problems and Solutions article if you need more help.
This problem is common in many Mercedes-Benz models including Chrysler Crossfire, Dodge Sprinter Vans and SLR McLaren.
Mercedes-Benz Transmission Valve Body Electrical Conductor Plate (5-Speed 722.6xx Transmission) 1402701161 => 1994-1997 5-Speed A/T SL320 / 1994-2006 5-Speed A/T SL500 / 2003-2007 5-Speed SL55 AMG / 1994-2007 SL600 / 2005-2007 SL65 AMG / 1998-2004 SLK230 / 2002-2004 SLK32 AMG / 2001-2004 SLK320 / 2010 Mercedes-Benz Sprinter 2500 3500 / 2003-2009 Dodge Sprinter 2500 3500 / 2002-2010 Freightliner Sprinter 2500 3500
MERCEDES-BENZ TRANSMISSION IMPACTED MODELS 1997-2007 C230,C240,C32,C320,C55,CL500,CL55,CLK320,CLK500,CLK55,E300.E320,E420,E430,E500,E55,ML320,ML350,ML430,ML500,ML55,S430,SL320,SL500,SL55,SL600,SLK320,SLK32,SLK320,AMG,SPRINTER