MMI Stopped working... PLEASE HELP

[Stickytreez]

I have a 2015 Audi a4 and my story is below please help the dealership has quoted me a disturbingly high price.

So my MMI randomly shut off last night on my way home, no prior issues prior to last night.
I took it to the dealership and they are saying the following.

"no communication with 5f or radio module. checked power and ground at 5f unit in dashboard, power and ground are present,
checked power and ground at radio module, power and ground are present, recommend replacing 5f unit to start,
radio module could not have communication as the 5f unit is not functioning"

this was after I was charged $165+tax for the diagnosis.

they then presented me with an estimate which I will attach below.
they have quoted me nearly $10.5K to replace the 5f module
but the part number they have given is 4g0035082g, looking this up it seems this is the HD radio receiver

IMG_0551.jpg

Please help as I'm not willing to spend that much to repair this and am looking for some expertise on this matter as to what I should do and how I would go about fixing this for much less

[Grouch]

What in the world. Would buy an RSNAV unit and save yourself the money unless you absolutely love your MMI unit. I never take my car to the dealer unless it's for warranty work. Get a 2nd opinion from a reputable mod shop.

[Smac770]

I presume you do not have the B&O sound system? Since they never refer to the J525 sound system amplifier. But then they go and list the part number for the Radio unit for the B&O sound system? Very confused.

Which means the MOST bus consists of the J533 CAN Gateway, J794 MMI 3G+ controller, and the R radio with integrated amplifier.

If any of the units are not working, the whole ring goes down. And since the J794 is not connected via CAN, only MOST, if any MOST unit goes down, you can no longer communicate with the J794, which is the ring master. Brilliant design, Audi.

"replacing J794 to start", really? That's their problem isolation path? Not that Audi gives any other option, since Audi removes the telnet terminal from the J794, so you cannot diagnose the J794 whatsoever. Did they even bother to put an optical bypass plug on the radio end of the optical cable to make sure the radio unit was not taking the ring down? Where's the ring-break diagnosis? That was a complete waste of $165. You know nothing more now than you did before (well, that we collectively knew before).

$9000 CAD for the radio? Wtf is that. And it's really odd they listed it as the 082 part number instead of the 080 part number. https://parts.audiusa.com/p/51128847/4G0035080G.html So yeah, $9k is a bit absurd.
But again, 080/082 is for the B&O sound system, not the standard sound system. That would be 056. You need to confirm if you have a J525 or not.

The part number for the MMI 3G+ controller should have been 8R1 035 746 G or such. Close to $4k USD for a new one, https://parts.audiusa.com/p/64716608/8R1035746G.html. So I'd be looking used on eBay. Here's an example of one I would *not* buy, https://www.ebay.com/itm/165298469194 Notice the plugs are yanked off the two RF connections along the back left side. WTF. But you should be able to find one for under $1k used easily. You can replace it yourself in less than 15 minutes if you have the MMI removal keys ($10 on eBay). But you'll still need the dealership to bless the union because of that component protection bs. One hour labor.

It would be better if you pulled out your current unit and confirmed the part number on it, or if you had VCDS and had a scan log showing the part numbers to confirm.

[Stickytreez]

What in the world. Would buy an RSNAV unit and save yourself the money unless you absolutely love your MMI unit. I never take my car to the dealer unless it's for warranty work. Get a 2nd opinion from a reputable mod shop.

Ya im completely distraught with the price they quoted me I told the guy they are fucking crazy and left.
but I do need to get the issue fixed I just dont know what I actually need to get replaced as the part numbers dont line up with what they have said which is why I am so confused and came here looking for someone with expertise in the matter!

[4xaudi]

The MMI in my 2013 allroad would randomly shut down or go into a constant reboot mode. I bought a used unit off Ebay and swapped the hard drives. Took maybe 2 hours.

[Stickytreez]

I presume you do not have the B&O sound system? Since they never refer to the J525 sound system amplifier. But then they go and list the part number for the Radio unit for the B&O sound system? Very confused.

Which means the MOST bus consists of the J533 CAN Gateway, J794 MMI 3G+ controller, and the R radio with integrated amplifier.

If any of the units are not working, the whole ring goes down. And since the J794 is not connected via CAN, only MOST, if any MOST unit goes down, you can no longer communicate with the J794, which is the ring master. Brilliant design, Audi.

"replacing J794 to start", really? That's their problem isolation path? Not that Audi gives any other option, since Audi removes the telnet terminal from the J794, so you cannot diagnose the J794 whatsoever. Did they even bother to put an optical bypass plug on the radio end of the optical cable to make sure the radio unit was not taking the ring down? Where's the ring-break diagnosis? That was a complete waste of $165. You know nothing more now than you did before (well, that we collectively knew before).

$9000 CAD for the radio? Wtf is that. And it's really odd they listed it as the 082 part number instead of the 080 part number. https://parts.audiusa.com/p/51128847/4G0035080G.html So yeah, $9k is a bit absurd.
But again, 080/082 is for the B&O sound system, not the standard sound system. That would be 056. You need to confirm if you have a J525 or not.

The part number for the MMI 3G+ controller should have been 8R1 035 746 G or such. Close to $4k USD for a new one, https://parts.audiusa.com/p/64716608/8R1035746G.html. So I'd be looking used on eBay. Here's an example of one I would *not* buy, https://www.ebay.com/itm/165298469194 Notice the plugs are yanked off the two RF connections along the back left side. WTF. But you should be able to find one for under $1k used easily. You can replace it yourself in less than 15 minutes if you have the MMI removal keys ($10 on eBay). But you'll still need the dealership to bless the union because of that component protection bs. One hour labor.

It would be better if you pulled out your current unit and confirmed the part number on it, or if you had VCDS and had a scan log showing the part numbers to confirm.

What’s the best way for me to determine what audio system I actually have be it b&o or not

I’m pretty sure my car is a 2.0 progressive s-line
I'm also pretty sure I have an B8.5 a4

I ran a scan with my OBDeleven
And opened the 5f category and radio category does this help at all?
E5050340-E478-484F-AD56-4AE2508EA73A.jpg

[DrGER]

WOW, that repair estimate is absurd !

Your system is NAR MMI 3G+, main unit PN 8R1035664G, for MY2015 production in non-US (i.e., Canadian) models. No SIM card or 3G data modem built-in.
But that's interesting -- your OBDeleven can query J794 -- do you get any fault codes from Address 5F ?
If you need a new main unit J794, you can use any of the VAG part numbers starting with 8R1035664 (starts with 'A' for MY13, ends with 'J' for MY16, difference is likely firmware version/nav database installed).

Also: B&O systems will have Address 47, Sound System (J525), noted above, with amplifier PN 8T1035223A. But if your speakers don't have B&O fascia, then what's the likelihood of B&O ? Production code 9VK is 'Sound Package "1"' (B&O), but on our MY14, that PR code isn't listed on the vehicle info sticker (I got it from erWin during my 24 hour subscription). Ask your dealer for a full list of the PR codes for the VIN (useful when looking for proper VAG part numbers based on build options). --g

PS: Non-SIM MMI 3G+ main units are out there -- for example: https://www.ebay.com/itm/194776110778
But the question is: is that what's causing this problem ?

[Smac770]

This is where OBDeleven still has work to do. VCDS, one can just do an autoscan, save to log, post log, everything one might ask about is already there to be looked up.

So the remaining question is do you have the control module at address 47. Just look in the left rear, do you have a single radio unit or a radio unit and an amp on top of that? This would be the amp, https://www.ebay.com/itm/372690478872

I'm curious. How is your OBDeleven talking to the J794 (5F) to pull the unit information? Is that historical information, or was the unit not working but it's working now? The issue is intermittent?

As your screen cap points out, you have the 664 type of the J794, not the SIM enabled 746 type. So clearly look for that one when looking for a replacement.

I still think you need to get a bypass plug and check if the system works when the radio (and amp, if applicable) are bypassed. But if the issue is intermittent, it could well just be the J794 starting to flake out.

[Stickytreez]

This is where OBDeleven still has work to do. VCDS, one can just do an autoscan, save to log, post log, everything one might ask about is already there to be looked up.

So the remaining question is do you have the control module at address 47. Just look in the left rear, do you have a single radio unit or a radio unit and an amp on top of that? This would be the amp, https://www.ebay.com/itm/372690478872

I'm curious. How is your OBDeleven talking to the J794 (5F) to pull the unit information? Is that historical information, or was the unit not working but it's working now? The issue is intermittent?

As your screen cap points out, you have the 664 type of the J794, not the SIM enabled 746 type. So clearly look for that one when looking for a replacement.

I still think you need to get a bypass plug and check if the system works when the radio (and amp, if applicable) are bypassed. But if the issue is intermittent, it could well just be the J794 starting to flake out.

So I found a history report in my OBDeleven from 2020 and can confirm there is no address 47 at all, I will take some pictures of the components my car has as well as the trunk tomorrow when i wake up and post them here for reference.

If I run OBDeleven now 5f and radio don’t even show up in the list I should have mentioned that the images I posted where from history in my OBDeleven and not from a current scan as they do not show up in a current scan

I just want to say thank you so much to everyone who is trying to help me with this issue I greatly appreciate your time and effort.

also on a side note the dealership told me that the car isn't even recognizing that it has a radio installed if that changes things at all.

[DrGER]

So I found a history report in my OBDeleven from 2020 and can confirm there is no address 47 at all, I will take some pictures of the components my car has as well as the trunk tomorrow when i wake up and post them here for reference.

If I run OBDeleven now 5f and radio don’t even show up in the list I should have mentioned that the images I posted where from history in my OBDeleven and not from a current scan as they do not show up in a current scan
...
also on a side note the dealership told me that the car isn't even recognizing that it has a radio installed if that changes things at all.

The dealer confirms what your OBDeleven says: Address 5F (J794) and related audio modules are down (as SMac notes above).
Next step might be to get a fiber optic bridge (VAG PN 4E0-973-802) and try to isolate the module that causes the MOST ring to fail (also noted above).

ETKA tells us that the original radio module (4G0035082G), which drives the speakers, is replaced by VAG PN 4G0035080G (variants C, D, E available). --g

[RPMtech147]

Shot in the dark, and the most diag on Audi is some of the worst.

I've replaced literally dozens of AMPs on VAG cars....It's the only thing I've ever seen bring the most down. *Sometimes* you can bypass the amp and the system will come back up, and at least you know it's the amp. Get a most lolli off Amazon and start bypassing modules. VCDS is somewhat lack-luster with its most diag tool but maybe I've just never had any success with it.

You can also try and throw a used amp from Ebay in there. It will let the radio power up but it will give you component protection faults and do funky stuff (just did one in an A6 and until I programmed the amp, it would only play out of 1/2 the speakers)

A Euro shop that knows Awdee *should* be able to program used amps. We do it all the time with a company that can remote in with ODIS.


https://www.amazon.com/Optical-Adapt...s%2C120&sr=8-5

[Stickytreez]

This is where OBDeleven still has work to do. VCDS, one can just do an autoscan, save to log, post log, everything one might ask about is already there to be looked up.

So the remaining question is do you have the control module at address 47. Just look in the left rear, do you have a single radio unit or a radio unit and an amp on top of that? This would be the amp, https://www.ebay.com/itm/372690478872

I'm curious. How is your OBDeleven talking to the J794 (5F) to pull the unit information? Is that historical information, or was the unit not working but it's working now? The issue is intermittent?

As your screen cap points out, you have the 664 type of the J794, not the SIM enabled 746 type. So clearly look for that one when looking for a replacement.

I still think you need to get a bypass plug and check if the system works when the radio (and amp, if applicable) are bypassed. But if the issue is intermittent, it could well just be the J794 starting to flake out.

Ok sorry for the delay, I’ve gotten a bypass loop unplugged the radio unit in trunk used the loop and turned on the car and still no screen, so what is my next step do I have more modules behind the glovebox or does this confirm my J794 needs to be replaced? Also if that’s the case would I just buy a j794 used and swap the whole unit or just the hdds inside? Also could it be my buttons causing it to not work? I just don’t want to go replace a module and it still not work and end up being something else

[DrGER]

I'll defer comment on whether the control panel E380 might cause the entire system to fail to those more knowledgeable (but the wiring diagram suggests to me it's more likely a failed J794 will result in control panel E380 not working, too).

OP, do you know car-part.com ? Searching for Year = 2015, Make/Model = Audi A4, Part = Radio/CD, Area = Canada > player, (multimedia), (dash mounted), ID 8R1035664E: returns a few hits, including a few 8R1035664E (3G+ without data modem/SIM slot) at LKQ in Niagara Falls. Turns out I got a mid-line BCM for our VW wagen from them recently (via eBay); still waiting for warmer weather to do that fog lamp mod in the car, but the part was packaged well and was undamaged. You might give them a call if you need to replace your J794. --g

[Stickytreez]

I'll defer comment on whether the control panel E380 might cause the entire system to fail to those more knowledgeable (but the wiring diagram suggests to me it's more likely a failed J794 will result in control panel E380 not working, too).

OP, do you know car-part.com ? Searching for Year = 2015, Make/Model = Audi A4, Part = Radio/CD, Area = Canada > player, (multimedia), (dash mounted), ID 8R1035664E: returns a few hits, including a few 8R1035664E (3G+ without data modem/SIM slot) at LKQ in Niagara Falls. Turns out I got a mid-line BCM for our VW wagen from them recently (via eBay); still waiting for warmer weather to do that fog lamp mod in the car, but the part was packaged well and was undamaged. You might give them a call if you need to replace your J794. --g

Yes I know car-part.com very well
I Just want to make sure that if I’ve bypassed the radio in the trunk and the screen still doesn’t work that means it’s the J794 that needs to be replaced and not something else before I order the j794

[Stickytreez]

I'll defer comment on whether the control panel E380 might cause the entire system to fail to those more knowledgeable (but the wiring diagram suggests to me it's more likely a failed J794 will result in control panel E380 not working, too).

OP, do you know car-part.com ? Searching for Year = 2015, Make/Model = Audi A4, Part = Radio/CD, Area = Canada > player, (multimedia), (dash mounted), ID 8R1035664E: returns a few hits, including a few 8R1035664E (3G+ without data modem/SIM slot) at LKQ in Niagara Falls. Turns out I got a mid-line BCM for our VW wagen from them recently (via eBay); still waiting for warmer weather to do that fog lamp mod in the car, but the part was packaged well and was undamaged. You might give them a call if you need to replace your J794. --g

So I just pulled my dash unit and this is what I haveBBB65EF3-CB03-4A45-9618-8ABB6245E8EC.jpg

[DrGER]

Given that the 664x MMI 3G+ main units don't have 3G data modems (and that 3G is going away soon anyway), any working 664x variant will replace yours, though you'll likely need to update the MMI firmware and navigation database (I can point you to both of those if you need them). BTW, I'm not convinced that a failing/failed HDD by itself will cause J794 to fail, also, given that 99% of the QNX system resides in flash memory, and only a few non-essential bits live on the HDD (e.g., the Google Earth package binaries). --g

[Stickytreez]

Given that the 664x MMI 3G+ main units don't have 3G data modems (and that 3G is going away soon anyway), any working 664x variant will replace yours, though you'll likely need to update the MMI firmware and navigation database (I can point you to both of those if you need them). BTW, I'm not convinced that a failing/failed HDD by itself will cause J794 to fail, also, given that 99% of the QNX system resides in flash memory, and only a few non-essential bits live on the HDD (e.g., the Google Earth package binaries). --g

so start by replacing my J794 since the loop bypass on radio the system was still not functioning and go from there? It may just be the case that both parts died at the same time perhaps

[DrGER]

so start by replacing my J794 since the loop bypass on radio the system was still not functioning and go from there? It may just be the case that both parts died at the same time perhaps

Unless someone else (Smac?) has further observations/suggestions, starting with a replacement J794 seems reasonable. My understanding is the Component Protection (CP) won't prevent the replacement from powering on and providing some basic functionality; beyond that, I don't have direct experience, so couldn't say for certain. Removing CP is a trip to the dealer; you have OBDeleven, so if any coding is needed (say, to enable the Green Engineering Menu), you can do that. --g

[Smac770]

If it's confirmed there's no amp, and the system continued to be non-functional with the radio bypassed (the bypass loop goes on the optical cable plug that would otherwise be plugged into the radio, not in the radio jack), then greatest likelihood is that something is wrong in the J794. So replacing it would be the path of least effort for greatest likelihood of progress. The system should come up and you should be able to access things like car menu. But you won't have any audio from the radio/CD/AMI until the component protection is reset by the dealership or a capable shop.

[Stickytreez]

Thanks for all the help guys I will now source a j794 unit install it and post updates, I greatly appreciate everyone’s help and love how supportive the Audi community is 😃

[BG_AG]

I will be watching this thread closely as my MMI just went dark. Ill wait for Bypass loop to come in the mail before posting any questions :)

[DrGER]

OP, if you find that a replacement J794 gets you going again, I would be interested to know if the HDD in your "failed" main unit still works & can be read (say, for potential disk image cloning for SSD conversions). --g

[Militant-Grunt]

What in the fuck? A new 5F module on a B8 is expensive, but not 10k expensive. Its around 1500-2k for a B8 unit and 2500ish for a C7, something is very wrong here. I suggest you contact Audi Canada (if thats where you're located) and report on the dealer. That is absurd.

[A4 Centaur]

^ Concur. Best of luck for figuring this out quickly and cost effectively!

[Stickytreez]

I've already sourced and ordered a new 5f unit for a total whopping cost of $265 cad shipped to my door, I have also filed a complaint with the president of Audi Canada demanding that they return my diagnostic fee that told me nothing more than I already knew and requested that they remove the hardware protection on my new device free of charge in light of the fact that they tried to steal 10's of thousands of dollars from me, now I wait for the response the best part is I have all the paperwork which makes the dealership look totally shady.

[Theiceman]

I've already sourced and ordered a new 5f unit for a total whopping cost of $265 cad shipped to my door, I have also filed a complaint with the president of Audi Canada demanding that they return my diagnostic fee that told me nothing more than I already knew and requested that they remove the hardware protection on my new device free of charge in light of the fact that they tried to steal 10's of thousands of dollars from me, now I wait for the response the best part is I have all the paperwork which makes the dealership look totally shady.

Hope you get some traction.... But Audi is known for that stuff and they will tell you dealer operates independently.

Sent from my Pixel 6 using Audizine Forum mobile app

[SDF1]

I've already sourced and ordered a new 5f unit for a total whopping cost of $265 cad shipped to my door, I have also filed a complaint with the president of Audi Canada demanding that they return my diagnostic fee that told me nothing more than I already knew and requested that they remove the hardware protection on my new device free of charge in light of the fact that they tried to steal 10's of thousands of dollars from me, now I wait for the response the best part is I have all the paperwork which makes the dealership look totally shady.

What I've been told from a friend that works at a dealership is only time they react is when you post bad reviews on them. Just saying.

Maybe something like - The dealership wanted me to pay the same amount for a brand new engine but to replace the radio in my car...lol

[JeeprageII]

I will be watching this thread closely as my MMI just went dark. Ill wait for Bypass loop to come in the mail before posting any questions :)

Did you ever diagnose and fix your display?