New member from Hawaii

[Alohajim]

Aloha All. Have owned a 2014 Blue B class with 60k miles for nine years. Zero issues and a great car (wife's car). She has kept it in showroom condition. Have been a very happy owner but now dealer says I need a new DU for 22k so I joined this forum in the hopes of resolving the problem by modifying/deleting a sensor, - this car is just too nice to give up on. Best of luck to all.

 

[tankmania]

Aloha All. Have owned a 2014 Blue B class with 60k miles for nine years. Zero issues and a great car (wife's car). She has kept it in showroom condition. Have been a very happy owner but now dealer says I need a new DU for 22k so I joined this forum in the hopes of resolving the problem by modifying/deleting a sensor, - this car is just too nice to give up on. Best of luck to all.

Why do you need a new DU? Have you been having error codes? Do you have coolant leaked into your motor?

 

[Alohajim]

I don't think it needs a new DU or to worry about a coolant leak. The dealer told me that coolant had leaked into the DU and their only fix was for a new DU for 22k. But when I asked him how much coolant they added he said zero and I have not added any coolant in nine years of ownership. When you look at the coolant level, it's fine, not low. There is evidence of moisture on the speed sensor, but so what? the coolant is obviously not 'leaking' and with no mechanical issues the only thing stoping the car is the software. I was trying to find out what sensor is delivering this error code and how to bypass it.

 

[LondonWdd14289ownwr]

I don't think it needs a new DU or to worry about a coolant leak. The dealer told me that coolant had leaked into the DU and their only fix was for a new DU for 22k. But when I asked him how much coolant they added he said zero and I have not added any coolant in nine years of ownership. When you look at the coolant level, it's fine, not low. There is evidence of moisture on the speed sensor, but so what? the coolant is obviously not 'leaking' and with no mechanical issues the only thing stoping the car is the software. I was trying to find out what sensor is delivering this error code and how to bypass it.

I believe there is a small amount of coolant leak from the bearing seal . The small amount may looks negligible but may reduced the insulation resistance of the drive unit . When the resistance is below a certain level, the high voltage control system which turns the drive motor, senses this and will automatically stop the high voltage to the motor ( for safety reasons) . This can be repaired by taking out the motor , changing the leaking bearing seals, also few other bearing and seals. Mercedes don't do gearbox/ drive motor so will replace it with a new one. but quite a few independent garages do repair the old one .The motor is then cleaned and dried out ( sometimes if damage is bad , then a replacement motor is required) . Most garages can also do some modifications like coolant delete( which I don't recommend) or adding drain holes so the motor doesn't get damaged again in future is the seals fail again

 

[lensovet]

I don't think it needs a new DU or to worry about a coolant leak. The dealer told me that coolant had leaked into the DU and their only fix was for a new DU for 22k. But when I asked him how much coolant they added he said zero and I have not added any coolant in nine years of ownership. When you look at the coolant level, it's fine, not low. There is evidence of moisture on the speed sensor, but so what? the coolant is obviously not 'leaking' and with no mechanical issues the only thing stoping the car is the software. I was trying to find out what sensor is delivering this error code and how to bypass it.

The dealer is right in that MB doesn’t repair this, they replace the entire unit.

The amount of coolant leaking doesn’t need to be a lot. There’s no way for you to “check” the level of coolant, it’s a sealed system that has nothing to do with the accessible coolant under the hood.

Search this forum for coolant delete. You’re lucky that the car lasted this long without issues. I was not so lucky and hit this problem before I hit 6 years with much fewer miles.