Mercedes-Benz COMAND control knob not working, DIY Fix

The rotating function of certain Mercedes-Benz COMAND control knobs is known to stop working. All other functions will continue to work.

  • Pressing the rotary wheel is no reaction on the monitor (Comand APS)
  • Functions to the left, right, up, down, press Back button, cancel button may still work.

How to fix Mercedes command knob not working

There is no need to replace the entire COMAND unit as suggested by Mercedes-Benz. Save money by simply replacing the broken plastic shaft to a new aluminum version of it.

You can replace the broken shaft yourself, or send your Mercedes COMAND unit to a company such as IE Works, which will repair your unit and return back to you.

Here is a link where you can order their service: Mercedes COMAND Broken Shaft Service 

Parts Required:

Tools Required:

  • TORX T10 Screwdriver
  • TORX T8 Screwdriver
  • Slotted 1/8" Screwdriver

Mercedes COMAND Knob Replacement Instructions: 

Step 1. Remove the unit from the center console of the vehicle. (This process will vary in different vehicles) When removing the switch assembly, be mindful of the wiring connector. Rough handling could lead to broken wires.

Removed Switch Assembly

Step 2. Remove the knurled knob cover with a flat screwdriver. Rotate the knob and lift the cover from the knob incrementally. Often times the cover is seized to the knob and may take some time for it to shift. Avoid scratching the cover and top surface of the assembly. The assembly has sharp edges; wear protective gloves as the hand can slip during this step.

Use Small Flat ScrewdriverLift the knurled cover

Step 3. Remove the ring and cap with a flat screwdriver. The cap holds on with an adhesive film. Handle with care as it will be reused. 

Remove Ring

Remove Cap

Step 4. Remove the knob top screw with a T8 screwdriver. 

Use T8 Screwdriver

Step 5. Remove the ten screw on the bottom with a T10 screwdriver. 

Remove Bottom Screws

Separate the top and bottom component

Step 6.  Lift and remove the stacked four components. Try to keep them in the same position for an easier installation during assembly.

Four Components

Step 7.  Remove the four levers with a flat screwdriver. There are two tabs holding the lever. Lift the lever from the middle top section of each side. 

Use Small Flat Screwdriver

Side View

Step 8. Remove the four lever holders with a flat screwdriver.  Pry the tab from the top then lift the lever holder. 

Use Small Flat Screwdriver

Side View

Step 9. Lift the electrical board away from the bottom section. Push the wire harness through the brackets as you lift the board.  

Electrical Board Removed

Step 10. Replace the broken plastic shaft with the new IE Works Shaft. It is recommended to apply metal-to-plastic grease on both ends of the new shaft.

New Shaft Installed

Assembling Tip: The stacked components in step six need to be installed in the same position as they were removed. 


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Mattie, 2019-05-20

The service link took me to eBay. Is the service still available?

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JimsAutoRepair, 2019-06-25

I agree here. An official Mercedes dealer will ALWAYS ask you to change the whole Knob! They just want to make money - while a lot of people dish out money on these, the best thing is how a whole cottage industry has developed around helping Mercedes owners save money through actually repairs and not just replacements that can cost 1000s of dollars.

While the above steps are pretty simple and straightforward, if you have NEVER repaired a car or a circuit, I'd suggest you do not try it.Things might go bad.. maybe ask a friend or a professional to help you.

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