Summary: A black Audi MMI screen or a car that has gone silent does not necessarily mean the screen itself has failed. The MMI is a set of separate parts — the display, the navigation unit that drives it, the amplifier and the fibre-optic ring that links them — and the fault is often somewhere other than the screen you are looking at. We bench test the unit you send, confirm the fault, repair it and return it ready to plug back in, with a Lifetime warranty.
This page works backwards from what your Audi is doing to the part that needs to come out, so the right unit reaches the bench first time. Other makes and systems are covered on our sat nav repair hub.
- What we repair: Audi MMI navigation units, including the A3 and S3 8V (2012–2020)
- Typical faults: no sound with a working screen, audio dropping out, black screen, freezing and restarts
- Where it sits: the navigation unit is a separate box from the screen
- How it is tested: on a rig that runs it as if it were still in the car
- On return: ready to plug in
- Warranty: Lifetime
Screen, navigation unit, amplifier, fibre-optic ring: which does what?
On an Audi with MMI, the screen you look at is the simplest part of the system. It shows the picture it is sent and, on many models, rises out of the dashboard when you switch on. The real work happens elsewhere:
- The display. It shows whatever the navigation unit sends it. Where the screen retracts, a small mechanism raises and lowers it every time you start the car.
- The navigation unit. The brain of the MMI, which Audi calls the information electronics control unit. On the A3 and S3 8V it runs the audio as well as maps, media and phone, so one failure inside it can silence the car while the screen carries on, or blank everything at once.
- The amplifier. On cars with an upgraded sound system, a separate amplifier drives the speakers. On larger models such as the A6 and Q7 it sits at the rear of the car.
- The fibre-optic ring. The modules pass audio and data to each other around a loop of fibre-optic cable, and every module is a link in that loop.
- The controls. The rotary controller and buttons on the centre console tell the rest of the system what you want.
Because these are separate parts, ‘the screen is black’ and ‘there is no sound’ describe what you notice, not which part has failed. The table below works from one to the other.
What you see, which part is likely, and what to send
Read across each row: what the car is doing, the part most likely behind it, and what should come to us or be checked first.
| What you see or hear | Most likely part | What to send, or check first |
|---|---|---|
| No sound at all, while the screen and menus work normally | A3 or S3 8V: the navigation unit, which carries the audio. Elsewhere, the amplifier or speaker wiring as well | A3 or S3 8V: the navigation unit. Other models: describe it to us first |
| Sound cutting in and out, or dropping once the car is warm | Often the early stage of the no-sound fault in the navigation unit | The navigation unit |
| Navigation voice and phone calls audible, but radio and music silent | Where a separate amplifier is fitted, it and the speakers are working; the fault is further up the chain | Tell us what still plays |
| Screen black, with navigation, radio and phone all gone | The navigation unit, once a blown fuse and low battery voltage are ruled out | The navigation unit, after a supply check |
| Screen black and no button lights either | Power reaching the system, as much as the unit itself | Fuses and battery voltage first, then the navigation unit |
| Screen will not rise, while the radio and parking sensors carry on | The display, or the mechanism that raises it | Ask us before removing anything |
| Stuck on the Audi logo, restarting on its own, or freezing mid-journey | The navigation unit failing to start up or stay running | The navigation unit |
| ‘System initialising’ that never clears, on a 3G-era car | Often the tuner or another module on the ring rather than the head unit | Send us the scan result first |
| Whole MMI dead, often just after a jump-start or battery change | A supply event exposing a weak navigation unit, or a break in the ring | Scan result first; usually the navigation unit |
| Controller or buttons dead, or a mute symbol that will not clear | The console controls, especially after a spill, or the navigation unit | Describe it; we confirm the part |
| Maps missing or position wrong, everything else normal | The navigation SD card, the GPS aerial or software | Reception and the card first |
| Battery going flat overnight | A module on the ring that is not going to sleep | A garage check for which module, then tell us |
Two questions narrow most faults quickly. Does sound carry on while the screen stays dark? Then the navigation unit is at least partly alive, and the display side is the place to look. Is the car silent while the screen behaves? On the A3 and S3 8V, that is the classic navigation unit fault.
For missing maps or a wrong position, our guide to sat nav signal problems covers the reception checks worth making first.
Why can a dead MMI turn out not to be the navigation unit?
The fibre-optic ring is the reason a whole MMI can go down while the navigation unit is healthy. Audio and data travel round the loop from module to module, and each module has to pass the signal on. If one stops working, loses power or is damaged, the loop breaks and everything after it goes quiet.
From the driver’s seat that looks like total failure: black screen, no sound, no radio. The broken link may be the amplifier at the back of the car, a tuner or another module on the ring. Water reaching a module at the rear, or a drink spilt over the console controls, can be enough to start it.
So the navigation unit should not be condemned on the symptom alone. A garage diagnostic scan will normally show which module has dropped off the ring; put the result on the repair form and we will tell you which unit should come to us. Once a unit is on our bench it runs on its own, so a fault that belongs elsewhere shows up as a unit that works.
MMI 3G, 3G Plus, RMC or MIB: which system does your Audi have?
Audi has fitted several MMI generations, and one model can carry different systems depending on its year and specification. The table shows where each system appears, and the right-hand column shows where we stand.
| System | Models it appears in | With us |
|---|---|---|
| MIB | A3 and S3 8V (2012–2020); also listed on the A4, A5, A6, A7 and Q7 | A3 and S3 8V repaired by post |
| MMI 3G Plus | A1, Q3, A4, A5, Q5, A6, A7, Q7, A8 | Ask us with the part number |
| MMI 3G High | A4, A5, Q5, A6, Q7, A8 | Ask us with the part number |
| MMI 3G Basic | A4, A5, Q5, A6, Q7 | Ask us with the part number |
| RMC | A1, Q3, A6, A7 | Ask us with the part number |
For the 8V, the repairs are listed as the Audi A3 (8V) MMI (2012 – 2020) Navigation unit and the Audi S3 (8V) MMI (2012 – 2020) Navigation unit. For any other Audi, send the model, year and the part number from the unit’s label, and we will confirm before it comes out.
Across the wider Volkswagen group we also repair RNS510 and RNS810 navigation, and BMW owners have a dedicated iDrive repair page.
What wears out an Audi navigation unit?
The faults in the table come back to a handful of causes:
- Heat. Tucked behind the dashboard, the unit warms up on every journey and every sunny day parked. Sound that drops out once the car is warm is the early warning.
- Constant load. It powers up on every journey and runs audio, maps, media and phone together, and age tells on anything worked that hard.
- Supply dips. A flat battery, a battery change or a jump-start sends a disturbance through every module on the ring. A unit that was already weak may not come back from it.
- Moisture. Spills near the console controls, and water in the boot reaching modules and connections at the rear.
- Mechanism wear. A retracting screen is raised and lowered on every start, and its mechanism wears like any moving part.
A reset can wake a struggling MMI for a day or a week. When the same fault keeps returning, the cause is physical, and that is what the bench repair deals with.
Sinspeed · Audi MMI repairs
Not sure which part is behind it? Tell us what still worksList what has gone and what carries on — screen, sound, radio, navigation, buttons — with the model and year. We will tell you whether the navigation unit is the part to send.
Fault confirmed on the bench first · Returned ready to plug in · Lifetime warranty
Why does your original unit go back in ready to plug in?
Every Audi navigation unit is matched to the car it was built for. A unit from another car — used, exchanged or new — has to be coded to yours with dealer-level equipment, and until it is, Audi’s component protection can leave it only partly working.
The unit you send already belongs to your car. Repaired, it keeps that identity and reconnects ready to plug in, the way our A3 and S3 units are returned.
One fitting fact is worth knowing. If someone has already tried to code a different unit to the car, your original has to be matched back at refit, a coding step the fitting garage carries out with dealer-level equipment as part of the job.
Bench testing also tells you something a replacement cannot. If your unit tests healthy, the fault is elsewhere on the ring, and you know that before a new unit has been ordered, coded and found to change nothing.
Sending your Audi MMI unit to us, step by step
- Tell us which functions have gone
Use the repair form to give the model, year and which of the screen, sound, radio, navigation and buttons still work, plus anything a diagnostic scan has reported.
- Your garage removes it and posts it
Your garage takes the navigation unit out, or you do if you are comfortable with interior trim. Pack it well and post it; from the moment it arrives, the job is ours.
- Run as though it were still in the Audi
In our ESD-safe workshop, the unit goes onto a bespoke Hardware-in-the-Loop rig that powers it up and simulates heat, vibration and load. The reported fault is reproduced and confirmed before any work starts.
- Repaired, then put through the same tests
The confirmed fault is repaired and the unit goes back on the rig, where sound, picture output and navigation are all checked again.
- Back to you, ready to reconnect
It returns ready to plug in, with a Lifetime warranty. If another unit has been coded to the car in the meantime, the garage matches your original back as part of refitting.
Audi MMI repair: questions owners ask
Sinspeed · Audi navigation units
Send the unit that belongs to your Audi, and get it back workingBook it in on the repair form, or check with us first if your Audi is not an A3 or S3 8V, or a scan points somewhere other than the navigation unit.
Hardware-in-the-Loop rig testing · ESD-safe workshop · Lifetime warranty
Final thoughts
A dark screen is the part of an MMI fault you notice, and often the part least likely to be behind it. Working out whether the navigation unit, the amplifier or a link in the fibre-optic ring has failed is what puts the right unit on the bench.
When the navigation unit is the one, repairing it keeps the unit matched to your car, so it goes back in ready to plug in and carries a Lifetime warranty.