The Audi A4 B9 was produced in 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023 and 2024 with the designations B9 and 8W. During this time, the model underwent restyling. In this article you can find a description of the fuses and relays of the Audi A4 S4 B9 with diagrams, their locations and photo examples of execution. Let’s highlight the fuse responsible for the cigarette lighter.
The purpose of fuses and relays may differ from those presented and depend on the year of manufacture, the level of electrical equipment and the region of delivery of your Audi A4 B9.
Passenger compartment
Fuse and relay box
Inside the car, the fuse and relay box is located on the left side, under the instrument panel.
Left-hand drive vehicles
Diagram
Right-hand drive vehicles
Diagram
Assignment
| Panel A (brown) | |
| 1 | Catalytic converter heating |
| 2 | Engine components |
| 3 | Exhaust doors, fuel injectors, air intake, engine heating |
| 4 | Vacuum pump, hot water pump, NOx sensor, particulate matter sensor, biodiesel sensor, exhaust doors |
| 5 | Brake light sensor |
| 6 | Engine valves, camshaft adjustment |
| 7 | Heated oxygen sensors, mass air flow sensor, water pump |
| 8 | Water pump, high pressure pump, high pressure regulator valve, temperature valve, engine mount |
| 9 | Hot water pump, engine relay, 48V starter-alternator, 48V water pump |
| 10 | Oil pressure sensor, oil temperature sensor |
| 11 | Clutch Position Sensor, 48V Starter Alternator, Water Pump, 12V Starter Alternator |
| 12 | Engine valves, engine mount |
| 13 | Engine cooling |
| 14 | Fuel injectors, drive system control module |
| 15 | Ignition coils, heated oxygen sensors |
| 16 | Fuel pump |
| Panel B (red) | |
| 1 | Anti-theft system |
| 2 | Drive System Control Module |
| 3 | Front left seat electronics, lumbar support, massage seat |
| 4 | Automatic transmission selector lever |
| 5 | Signal |
| 6 | Parking brake |
| 7 | Diagnostic interface (gateway control module) |
| 8 | Roof electronics control module |
| 9 | Emergency call and communication control module |
| 10 | Airbag control module |
| 11 | Electronic Stability Control (ESC), Anti-lock Braking System (ABS) |
| 12 | Diagnostic connector, light/rain sensor |
| 13 | Climate control system |
| 14 | Right front door control unit |
| 15 | Climate control compressor |
| 16 | Brake system reservoir |
| Panel C (black) | |
| 1 | Heated front seats |
| 2 | Wipers |
| 3 | Left headlight electronics |
| 4 | Panoramic glass roof/ sliding/ tilting sunroof |
| 5 | Left front door control unit |
| 6 | 12 volt socket, cigarette lighter |
| 7 | Right rear door control unit, right rear window regulator |
| 8 | All Wheel Drive (AWD) Control Module |
| 9 | Right headlight electronics |
| 10 | Windshield washer/headlight washer control module |
| 11 | Left rear door control module, left rear power window |
| 12 | Autonomous heater |
Fuse number 6 is responsible for the operation of the cigarette lighter.
| Panel D (black) | |
| 1 | Front seat electronics, seat ventilation, rear view mirror, rear climate control system control panel, heated windshield, diagnostic connector |
| 2 | Diagnostic interface, on-board network control module |
| 3 | Sound generator |
| 4 | Clutch position sensor |
| 5 | Engine start, emergency shutdown |
| 6 | Diagnostic connector, traffic information aerial (TMC) |
| 7 | USB connection |
| 8 | Garage door opener |
| 9 | Audi Adaptive Cruise Control, Adaptive Distance Control |
| 11 | Front camera |
| 12 | Right headlight |
| 13 | Left headlight |
| 14 | Transmission Fluid Cooler / Rear Window Wiper |
| 15 | Alarm and hands-free calling system |
| Panel E (red) | |
| 1 | Ignition coils |
| 2 | Climate control compressor |
| 5 | Left headlight |
| 6 | Automatic transmission |
| 7 | Dashboard |
| 8 | Climate control fan |
| 9 | Right headlight |
| 10 | Dynamic Steering |
| 11 | Engine starting |
Fuse box
There is another fuse box installed at the left end of the dashboard on the left side.
Diagram
Designation
- Convenient access and launch authorization control module (NFC)
- Audi phone, USB connector
- Head-up display
- Audi music interface, USB connection
- Front climate control panel
- Steering column lock
- Central display
- Instrument panel
- Volume control, Infotainment unit
- Light switch, switch module
- Steering column electronics
- Particulate matter sensor for climate control system
- Infotainment system
- Heated steering wheel, Electronic steering column
Luggage compartment
This fuse box is located in the luggage compartment on the left side, behind the trim.
Diagram
Allocation
| Panel A (black) | |
| 2 | Heated windshield |
| 3 | Heated windshield |
| 5 | Suspension control |
| 6 | Automatic transmission |
| 7 | Heated rear window |
| 8 | Rear seat heating |
| 9 | Left rear lights |
| 10 | Airbag, driver’s side seat belt pretensioner control module |
| 11 | Trunk lid lock, fuel filler flap lock, comfort system control unit |
| 12 | Luggage compartment lid |
| Panel B (red) | |
| 6 | Battery Power Interruption / Electric Compressor |
| Panel C (brown) | |
| 1 | External antenna |
| 2 | Audi phone booth |
| 3 | Right front seat electronics, lumbar support, massage seat |
| 4 | Lateral assistance |
| 6 | Tire pressure monitoring system |
| 7 | Convenient access and launch authorization control module (NFC) |
| 8 | Additional heating, tank module |
| 10 | TV tuner, data exchange and telematics control module |
| 11 | Auxiliary Battery Control Module |
| 12 | Garage door opener |
| 13 | Rear view camera, peripheral cameras |
| 14 | Right rear lights |
| 16 | Airbag, front passenger seat belt tensioner control module |
| Panel E (red) | |
| 3 | Exhaust treatment (Adblue) |
| 5 | Right trailer light |
| 7 | Trailer hitch |
| 8 | Left trailer light |
| 9 | Trailer socket |
| 10 | All Wheel Drive Control Module, Sport Differential |
| 11 | Exhaust treatment (Adblue) |
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Hi, my 2020 RHD S4 fuse box in the passenger footwell bears no relation – I can send you a photo. I need to identify which fuse to pull to isolate a function, but it’s not as per your page here.