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Stan
Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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hi i have a mercedes s class 320 cdi 2007. today i noticed

Customer Question

hi i have a mercedes s class 320 cdi 2007. today i noticed that the car was stuck in the 4th gear. tryed to stop/ restart the car without any luck. what could cause this problem? dont have any warning lights on dashboard to show otherwise. thanks
Submitted: 2 years ago.
Category: Mercedes
Expert:  Stan replied 2 years ago.
Stan :

Hello,
When there are fault codes in transmission control unit, there will be no warning messages. The symptoms are usually caused by failure of the transmission's valve body electronics.
To fix this, transmission fault codes must be checked to determine which components must be replace. All of them can be accessed without removing the transmission, only oilpan and valve body must be removed.

Stan :

Also old fluid must be checked for any metal particles to make sure no mechanical damage is present.

Stan :

Best regards,
Stan

JACUSTOMER-efwwula8- :

ok. thank you. i will take the car tomr to be checked via tester. i understood that if battery is disconnected for few minutes might help..is it true? also if i take car to a garage to be checked and its blocked in 4th gear it goes up to 40mph at 3000-3500 rpm. and a strange burn smell could be noticed. would this affect the car? regards, Alan

Stan :

Hi Alan,
If cycling the ignition does not help, battery disconnect is not likely to change anything.
The smell makes me think of slipping clutches in transmission, which is very bad. Check if there are any leaks seen under the car. It is not easy for the car to take off in 4th, which might also cause the burning smell. Driving with this symptom is not safe.