Hi everyone,

I have a 2017 CLS 63 S (C218 facelift) with COMAND NTG5.1 and Bang & Olufsen (MOST). My car did not come with option DAB / SA 537 from the factory, and I'm looking to retrofit it as close to OEM as possible (no USB dongles or FM injectors).

Most retrofit guides I've found online are for NTG4/4.5, so I'm trying to confirm what's required for NTG5.1 on the facelift C218, and from what I understand, the OEM-style retrofit should involve:

* DAB/DAB+ tuner module (MOST device, likely mounted in the trunk near the B&O amp)
* DAB-capable antenna amplifier/antenna path (Band III)
* Coax from antenna amp to tuner
* Inserting the tuner into the MOST ring
* Coding/activation afterwards (I can arrange coding, but I need help with hardware installation)

Important: I'm good with mechanical work (engine, drivetrain, etc.), but I have minimal experience with wiring/electrical, and I don't want to break the MOST ring or damage anything.

For reference, here is a VIN from a facelift CLS 400 with factory DAB that I'm using to compare wiring/equipment:
WDD2189611A124574

Questions:

* Has anyone retrofitted OEM DAB/DAB+ to an NTG5.1 facelift C218 (especially with B&O)?
* Which DAB tuner part number(s) work reliably with NTG5.1 in the C218?
* Does the retrofit require changing the antenna amplifier or even rear glass, or is it enough to add the correct antenna amp + coax?
* Where exactly is the cleanest place to insert the module into the MOST ring on the C218 with B&O?
* Any tips on avoiding common mistakes (fuse, MOST loop, coding order, etc.)?

I'm happy to pay for information or close assistance, if possible.

Thanks in advance.

 

Here's a short update based on my research on what needs to be ordered, replaced, and done afterward.

I've ordered the following parts:

A2229005117 – Digital Radio Control Unit (DAB Tuner, Digital Audio ECE)
A2129053406 – Antenna amplifier
12V Y MOST fiber optic cable (1× female, 2× male)
Fakra cable, male-to-male, 4 meters

Back in 2023, I asked Mercedes about the retrofit cost. They quoted around €4,200, which included replacing the rear windshield and some additional work, so I declined. This year, I decided to tackle the retrofit myself.

The general plan is as follows:

The DAB tuner box will be installed on the left side of the trunk and secured with brackets. I'll order the brackets once all parts arrive and I've confirmed that everything works correctly. The MOST connector will be removed from the Bang & Olufsen amplifier and connected to the Y-shaped MOST cable. One output will go back to the amplifier, and the second output will go to the DAB tuner box.

From what I understand, the tuner box receives its power directly via the MOST connection, since it has no other connectors apart from the MOST input and the antenna input. The antenna amplifier will also be installed in the trunk. I still need to determine the exact mounting location. It will be connected to the DAB tuner using the Fakra cable. This is just a high-level summary for now. I'll post pictures and a more detailed update next week once I start the installation.

As for coding, only variant coding should be required on HU55 (head unit) and possibly CGW_212 and IC_204. I'm not 100% sure about the last two yet, but I'll verify that during the process. There will probably be some trial and error along the way, but if I don't try, I'll never know.

 

Just a small clarification on the MOST side of things, as it’s easy to get tripped up here. MOST in Mercedes is purely optical – there is no power in the fiber connection.

Also, MOST has to remain a closed ring. A Y-shaped fiber cable won’t work, as the bus can’t be branched. To add a device, it needs to be inserted inline into the ring so that light continuity is preserved.

On the coding side, HU45/HU55 will need to be coded for the DAB tuner and the MOST configuration updated accordingly. CGW also needs the DAB option set so the device is correctly announced on the network. I’m not aware of any DAB-specific coding required in IC204.

Just mentioning this so you don’t end up chasing issues caused by the MOST topology rather than the hardware itself. Looking forward to seeing how the retrofit progresses.

 

Hey there, so I basically ****ed up then, or what? Left side is the main connector (I'm not changing the harness, just somehow connecting it) and right side is for the antenna, and using those stupid AI Chatbots, I thought that MOST gives power, although it was strange in the first place but since no experience with any retrofits I thought it was fine. So, then what to do? That Y cable I ordered won't work or what?

 

Here, look at the photos from this unit on eBay (mine did not arrive yet, but it's the same)

https://www.ebay.de/itm/389072592485

 

Also to add, from a German forum a guy wrote this (It's for an older NTG version)Generell werden folgende Teile zum DAB-Nachrüsten gebraucht (unabhängig von NTG-Version - aber natürlich technisch unterschiedlich bei NTG 4.x und 5S1):
-Receiver
-A-Verstärker
-RG174-Kabel mit Fakra-Kupplung (weiblich auf beiden Seiten)
-2x MOST-LWL
-MOST-Verbinder
-MOST-Stecker für Receiver
-MQS-Stecker für Receiver
-2x MQS-Pins

-2x 0,75qm Litzen für KL30(g) und KL31 (WakeUp kannst du dir sparen)

-Halter & Muttern für den Receiver

(Translated

Receiver
Antenna amplifier
RG174 cable with Fakra connector (female on both sides)
2× MOST fiber-optic cables
MOST coupler
MOST connector for the receiver
MQS connector for the receiver
2× MQS pins
2× 0.75 mm² wires for KL30(g) and KL31 (you can skip WakeUp)
Bracket and nuts for the receiver

Translation done)

Original thread in German: https://www.motor-talk.de/forum/nach...-t6592452.html

 

That MOST adapter you’re referring to should actually be fine. It’s actually a coupler, not a splitter. It simply opens the MOST ring at the female connector, and the ring is completed again once both male fiber plugs are connected. As long as both ends are populated, the optical ring remains intact.

You might also get lucky and find that the power harness for the DAB tuner is already present in the car, depending on the original equipment. If it isn’t, I may be able to help — a friend of mine has a CLS 500 that’s being used as a donor for a W124 E500 project, and the car is already apart, so taking a few reference photos wouldn’t be an issue.