Introduction: Mercedes Comand Controller Rotary Wheel Scroll Knob Switch Button Unit Shaft Repair Fix Kit Install Instructions Guide

The Problem

A plastic shaft within the scroller knob unit snaps causing the scroll function to no longer work on the screen.

It is a common fault on these vehicles for the comand controller knob to stop functioning correctly. A poor-quality plastic shaft within the controller knob unit snaps. This causes the common symptom of the scroller rotating as normal but for there to be no reaction on the screen. If all other functions are working except the scroll this indicates this shaft has deteriorated and snapped, this is an extremely common fault. Mercedes Benz fix is to replace the complete knob and button unit, this is extremely expensive and would only fail again..

Symptoms of the fault

Knob rotating but no response on the monitor. Knob works up-down-left-right but no rotation. When the wheel is turned, no reaction on the screen will be shown. All other functions such as confirming and tilting the controller are given.

Vehicles affected and compatibility

C-Class W204, C204, S204.

CLA-Class C117, X117.

E-Class W212, S212, A207, C207.

CLS-Class S218, X218.

GLK-Class X204, X218.

SLK-Class R172.

Associated part numbers:

A2048700779,A2048700879, A2048702058, A2048702158, A2048704558, A2048704658, A2048707458, A2048707558, A2128702851, A2128702951, A1728701258, A2048700179, A2128701351, A2128701451, A2128701551, A2128702751, A2048707658, A2048707758, A2048708851, A2048708951, A2048700579, A2048700679, A2048701258, A2048709558, A2048709758, A2048709958, A212870275, A2048700779, A2048702058, A2048700779, A2048702058.

This information is for guidance only, please inspect your comand knob unit to ensure compatibility.

Our solution

Restore full function with our replacement metal shaft.

Our part allows you to replace just the shaft within the knob unit which fails, without having to replace the complete unit at vast expense which would just fail again. Our shaft is CNC machined from billet aluminium then anodised. Beware of 3d printed, plastic and cast metal parts which could fail again. Our part will last the life of the vehicle. Using our part replace just the component that fails with an improved design part and restore full function permanently.

You will receive

1X Replacement CNC billet anodised aluminium rotary shaft.

Step 1: Lever Off Outer Part of Dial

Using a plastic screwdriver or pry tool; lever under the edge of the outer part of the dial as shown.

Lift this gently and in increments, push down on the center button of the dial to resist the lifting movement on the outer part of the dial.

Step 2: Remove Top Ring

Using a small screwdriver or pick, inset as shown and lift the top ring from the dial.

Step 3: Remove Top Button Cover

Using a plastic pry tool or screwdriver; slide under and lift off the top button cover.

Step 4: Remove Dial

Using a T10 Torx screwdriver loosen the screw and lift off the dial.

Step 5: Remove Screws

Using the T10 screwdriver remove the 8 screws from base of unit.

Step 6: Seperate the Two Sections of the Unit

Using plastic pry tools separate the two halves of the unit.

Around the center of the unit you will be able to see the joint of the two halves of the unit. Again gently and in increments level the two halves apart.

Take care not to damage the electrical ribbon which locates between the two halves.

Step 7: Locate the Plastic Gear

When separating the two halves of the unit this plastic gear shown may move out of position. Please note its correct position and orientation as shown.

Step 8: Remove Shaft Housing

Remove the plastic gear from the top of the shaft housing as shown.

Using the T10 screwdriver loosen the two screws on the housing and lift out of position.

Step 9: Remove the Shaft

Lift the black plastic shaft out of position.

The broken spindle is within this part.

Tip the shaft on its end and push out the two broken pieces of the spindle using the screwdriver.

Step 10: Remove the Circuit Board

Gently lift the circuit board out of position.

Step 11: Remove the Plastic Bush

Remove the plastic bush as shown.

Step 12: Remove Black Plastic Section

Remove black plastic section as shown.

Step 13: Remove Metallic Bush

Remove the metallic bush as shown.

Step 14: Remove All Lower Plastic Parts

Remove all the lower plastic parts as shown.

Sometimes by now these are all in a mess, remove all these loose black plastic parts.

Step 15: Rebuilt 4x Plastic Parts

These 4 black plastic parts here are key for reinstall.

Each of these 4 parts is made of 2 pieces of plastic, often these can become separated. Rebuild these so you have these 4 parts shown orientated as shown.

Step 16: Reinstall Lower Black Plastic Parts

Reinstall the base plastic part as shown.

Refit the 4x plastic parts on to each "leg" of the base plastic part as shown.

Step 17: Refit Components

Refit metallic bush.

Refit plastic section.

Refit plastic bush.

Step 18: Refit the Circuit Board.

The circuit board can be lowered back in to position.

This locates on the 4x lower plastic parts, it is important to ensure when fitting the PCB that these plastic parts do not move and bind.

Check at this stage that the 4x plastic parts haven't moved and gone rigid. Wiggle these parts with the screwdriver to ensure these parts can still be moved a little left to right and up and down. If you cannot move these, remove the PCB and re-seat these parts. This step is very important.

Step 19: Insert Our Spindle and Refit Shaft

Insert our new spindle in to the shaft as shown.

Refit the shaft and tighten the 2x screws.

Refit the top black plastic gear.

Step 20: Fastern the Two Halves of the Unit Back Together

Refit the two halves of the unit back together, ensuring the gear shown is fitted and orientated correctly.

The pins from the lower section of the housing push in to the x4 black plastic parts, again ensure these have not moved as this will make refitting the two halves very difficult.

Re-fasten the 8x screws.

Step 21: Refit the Top Dial

Refit the top dial.

Re-tighten the screw, you may need to push down on the dial for this to fasten.

Step 22: Refit Top Button and Outer Ring

Refit the top button in to the outer ring and push on to the dial.

Step 23: Refit the Outer Section

Note where this section locates on the dial and push in to position.

This completes the repair. If you need any further guidance on this install or would like to purchase the parts shown please call us on +44 01843 446643 or email us at

Please also check out our instruction guide on YouTube. Installation is carried out at installers risk, if unsure please contact us or a professional, X8R Ltd cannot be held responsible for any adverse result of installing this product or any injuries caused by install, if in doubt ask a professional. All images and texts are copyright X8R Ltd 2017