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Aug 15, 2026
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Hi all,


I’m hoping somebody with a bit more experience with MIB1 to MIB2 retrofits can point me in the right direction, as I feel like I’m very close to getting everything working properly.


The car is a 2014 SEAT Leon 5F which originally had a non-navigation MIB1 system.


Original setup


Original MIB1 main unit:


5F0 035 869 A


The original unit was connected directly to the factory Quadlock and the car appears to have the standard passive speaker system.


The original MIB1 long coding is:


04730000BE00000001111100010000000002F02048600000100000


Bytes 4–7 are:


BE000000


which appears to correspond to the 4-channel / 6 passive speaker 8RL configuration.


MIB2 retrofit


I have now fitted:


  • MIB2 main unit: 5QA 035 858 A
  • Hardware: H30
  • Software: 0359
  • 8-inch display: 5F0 919 606
  • MIB1 to MIB2 AliExpress Quadlock adapter harness
  • MIB2-compatible USB setup for Full Link
  • GPS antenna
  • Component Protection has been removed
  • Full Link / Android Auto is working

The MIB2 is currently coded:


04738001960A000011111101008808232F0100C60120010086


Bytes 4–7 are:


960A0000


which Xdiag/VCDS describes as:


4 channels / 6 passive speakers, PR-7ZF + 8RL


Byte 11 is currently:


01


which I understand to be the internal amplifier configuration.


The audio problem


This is the main issue I’m trying to solve.


With the MIB2 installed, I have sound from the tweeters/high-frequency speakers, particularly the A-pillar tweeters, so the MIB2 is definitely producing audio.


However, the door speakers are not producing the bass/low-frequency output.


I’m not sure whether the best terminology is that the high/mid frequencies are working but the low-frequency/bass channels are not, but essentially music sounds extremely thin because the door woofers aren’t playing.


Initially I suspected the AliExpress adapter harness, so I checked the brown 8-pin speaker connector with a multimeter.


I confirmed continuity through the adapter:


1 → 1
2 → 2
3 → 3
4 → 4
5 → 5
6 → 6
7 → 7
8 → 8


So the speaker section of the adapter appears to be straight-through rather than repinned.


The factory brown Quadlock wiring is:


Pin 1: red/purple
Pin 2: brown/green
Pin 3: brown/red
Pin 4: red/white
Pin 5: brown/purple
Pin 6: brown/blue
Pin 7: brown/black
Pin 8: brown/yellow


I also measured the speaker loads directly from the original car-side Quadlock:


Pins 1 & 5: OL
Pins 2 & 6: 3.5 Ω
Pins 3 & 7: 3.5 Ω
Pins 4 & 8: OL


So the two front speaker circuits are showing a healthy load of approximately 3.5 Ω.


The two rear circuits are genuinely open circuit, which appears to be a separate existing issue that I will investigate afterwards.


Important test with the original MIB1


I temporarily refitted the original 5F0 035 869 A MIB1 using the original factory wiring.


The front door speakers immediately worked again, including the low-frequency/bass output.


The MIB1 also correctly reported both rear bass speaker circuits as open circuit, which matches my multimeter readings.


So as far as I can tell, this proves that:


  • Front door speakers themselves are good
  • Front speaker wiring is good
  • Factory Quadlock wiring is good
  • AliExpress speaker wiring has continuity 1:1
  • MIB1 can correctly drive the front door woofers
  • MIB2 can drive the tweeters, but for some reason isn’t giving me the proper bass/woofer output

Coding/parameterisation question


I have also tried looking at the speaker coding.


BE000000, from my original MIB1, and 960A0000, currently on the MIB2, both appear to represent variants of the 6 passive speaker system.


Xdiag shows individual HT/TT speaker channel configuration within Bytes 4–7.


I have also been reading about MIB2 sound datasets/parameterisation, particularly the audio datasets such as 0x3000 / 0x3B00, and I’m wondering whether the replacement MIB2 has a sound dataset from a different vehicle/speaker configuration.


Xdiag gives me an NRC $31 “Routine Not Available or Parameter Out of Range” error when trying to access its Audio Parameter function, so I haven’t changed any datasets.


What I’m trying to establish


Has anybody experienced this after changing from MIB1 to MIB2 STD2 5QA 035 858 A?


Specifically:


Tweeters/high frequencies work, but the door woofers/bass do not, despite the front speaker circuits measuring 3.5 Ω and working perfectly when the original MIB1 is reinstalled.


Could this be:


  • Incorrect MIB2 sound dataset/parameterisation?
  • Incorrect Bytes 4–7 speaker configuration?
  • Something relating to Byte 11/internal amplifier configuration?
  • A known difference between MIB1 and MIB2 STD speaker output configuration?
  • Some additional coding/adaptation I’m missing?
  • Or is there something physically different about the outputs on the 5QA 035 858 A?

I don’t want to start randomly repinning the speaker wiring when the brown Quadlock already traces 1:1 and the same speaker circuits work correctly with the MIB1.


If anyone has done this exact retrofit, especially MIB1 5F0 035 869 A → MIB2 5QA 035 858 A, I’d really appreciate some guidance on what I should check next.


If it is a dataset issue, I’d also appreciate any advice on which dataset should be used for a Leon 5F with the standard 6-passive-speaker 8RL setup, and whether it can be read/written using Car Scanner, VCP, ODIS-E, or another method.


Thanks in advance.
 
Quite a few people on the board have swapped there mib1 to 2 in the past. Hopefully they will jump forward. I wouldn't think it would be the sound shaping parameter file but that is suppose to tally with the body. Think you need ODIS for that. @East Yorkshire Retrofits are the experts where you can buy kits for this but you went with mix and match I think. There are parameter files that tell the unit what your set up is, I have seen that in Obdeleven. Feels like you might have it set up for the Seat Sound System... that's a toggle I have seen in Obdeleven. Will step back now and leave it to people who have actually done this process to advice.