kainy

I've been on a fruitless search for the past couple of hours Can anybody confirm if an A8 mmi head unit can be used in an A6. Both are 4E0035729A, but I'm pretty sure the software versions are different. Can this be fixed with vag com coding or by swapping the eeprom?

raj99

If it's the same part number then it is interchangeable and you won't need to apply a different s/w ver since it will be the same for the h/w. It should be plug an play.

kainy

Thank you, I was assuming the same. I'll be able to test it today or tomorrow, while at the same time I have access to Odis in case there is a need to flash it (and may be kill it )

hrc4u

I have slight memory that it caused some issues..
I recall trying an mmi interface from an A8 when retrofitting my RVC.. Can't remember what issue it was though.. :/
But since you have odis access it might be possible to reflash sw to A6 version.. (can't even remember if that is possible with odis.. Or if you have to swap roms.. Hmm. :/)
Cheers /H

kainy

I got the unit today and decided to test it promptly, as there is some time to return it if it doesn't fit

Basically the HW number is the same, yes 4E0035729A, but the SW is 4E0910769Q. Regardless the unit was plug and play. I do not know why, but my startup screen was what i have chosen in my previous MMI's green menu (RS6... I know ), so I guess this is being saved up somewhere else?!

So on first glance everything worked. Even sound. Granted I have only two speakers working because of my amp issue but no signs of any Component protection limitations. Only one is that the system is in russian, as was the donor car I guess :P

I then fired up VCDS and after clearing all the errors in basically all units only one was left in the MMI about "driver identification' something. I guess that is because of the lack of keyless go. Interesting enough... no Component protection error code?! In the coding, as expected the unit has only settings for A8, but on first glance I could even leave it like that... everything seems to work fine, even the air suspension, but I did not test everything.

Regardless I'll leave the mechanic to try and flash the A6 firmware anyway, so that I'm sure all functionality is there. If that invokes the CP it will be a bummer

hrc4u

CP come on for me after a while when I changed the mmi..
Cheers /H

kainy

Sadly Odis failed to flash the mmi unit. Quoting the mechanic "the update didn't even want to try to start uploading". So I'm wandering if the unit would function 100% properly with the A8 software (once I remove the CP... when it comes on ) or should I remove it and just mod my old unit and add the video support (I already have all the components, but this was cheap enough to try it). I asked the dealership, just in case and they too stated that the unit cannot be flashed with the A6 software. It should be noted that they did also state that a swap from manual to automatic gearbox was not possible...

kainy

2 weeks later and still no CP is turned on, which is cool. The A8 MMI works fine with one exception - there is no visualisation for the climatronic controls, neither for the climatronic setup. I went throgh the green menu, and everything clima related was on. Does anybody has any idea on that?

Also still no luck with reflashing. All shops declined me because these units fail when reflashing too often... So I wanted to ask if anybody knows which chip holds the firmware, so I can try and physically swap it with the one from my previous MMI.

Shaun Todd

Hi there did you ever get your unit sorted as I did the same got one from an A8 for My A6 c6 as it had the fbas connection which I needed for retrofitting rear view cam ..
I have had it installed fit over a year now ..but still can't get the climate control function to show on the mmi screen like previous unit did .also any look on changing software to A6 as I think the A8 did drop this function for the mmi screen .