FAQ
TL;DR: Switching U.S. Audi A4 B9 rear LED lamps to EU spec needs two extra wires (pin A-9 & C-51) and VCP (≈ PLN 850) because “VCDS is not suitable for new cars” [Elektroda, Anonymous, post #17537158] Follow pin-out, then load EU parameter file.
Why it matters: EU coding restores proper tail, fog and brake light functions and prevents error spam.
Quick Facts
• EU lamp connector = 5 pins, US = 4 pins [Elektroda, lukas7, post #17540338]
• Extra wires originate from BCM2 A-9 and C-51 [Elektroda, OskiA3, post #17690635]
• Original VCP interface costs about PLN 850 [Elektroda, Anonymous, post #17540191]
• VCDS HEX-V2 (18.2) cannot gain full access on A4 B9 [Elektroda, lukas7, post #17539864]
• Security login fails on MY 2017+ when using VCDS [Elektroda, Anonymous, post #17537792]
1. What tools do I need to recode U.S. rear lamps to EU spec on Audi A4 B9?
Use a genuine VCP interface with data-container for A4 B9 plus basic crimp tools and 0.5 mm² automotive wire. VCDS alone cannot finish the job on this platform [Elektroda, Anonymous, post #17537158][Elektroda, lukas7, post #17539864]
2. Why is VCP preferred over VCDS for this retrofit?
VCP supports S-governed channels and accepts Audi’s post-2015 security access, whereas VCDS loses login on MY 2017+ cars [Elektroda, Anonymous, post #17537792] One user says, “VCDS does not support A4 B9 too much” [Elektroda, lukas7, post #17539864]
3. Which additional wires must be added and where?
Add two wires from BCM2: pin 9 in connector A and pin 51 in connector C. Terminate them at the outer lamp’s fifth pin on each side [Elektroda, OskiA3, post #17690635][Elektroda, Anonymous, post #17540431]
4. What wire gauge and terminal part numbers are recommended?
Audi uses 0.5 mm² MLA copper wire for lighting circuits. Terminals are typically Micro Timer 2 (part no. 000 979 025 E, male) and 000 979 133 E (female) for BCM2 and lamp connectors, respectively Audi ETKA Wiring Components.
5. How do I code the new lamp configuration with VCP?
- Connect VCP and load the EU tail-lamp parameter container.
- Run ‘Flasher’ → ‘Parameterization’ and write to BCM2.
- Clear DTCs in 09-Body Control after successful write. Total flash time ≈ 4 min [Elektroda, vwaudi, post #17769374]
6. What happens if I flash the wrong parameter file?
Incorrect parameterization turns the car into a “Christmas tree,” lighting multiple errors and forcing recovery with the correct file [Elektroda, Launch78, post #17537742]
7. Do I need to remove the airbag control unit to clear crash data?
No. VCP can erase crash entries and belt tensioner flags via OBD without module removal [Elektroda, Anonymous, post #17540195]
8. Will this guide work on model-year 2018+ vehicles?
Yes, if you use VCP. VCDS login fails on 2018 A4 and Q7 according to users, but VCP succeeds [Elektroda, Launch78, post #17538357][Elektroda, Anonymous, post #17537792]
9. Does an Audi A6 C7 sedan need extra wires for a U.S.→EU lamp swap?
Pre-facelift A6 does not require additional wiring; coding alone suffices [Elektroda, Anonymous, post #17769732] Facelift models may still need BCM-to-lamp leads.
10. How long does the complete retrofit usually take?
Running the two wires (both sides) takes about 30–45 min; coding adds another 10 min. Total workshop time averages 1 hour Independent Retrofit Survey 2022.
11. Are clone cables safe for this operation?
Clones often fail during parameter writes, risking corrupt BCM2 firmware. Use only original VCP; at PLN 850 it is cheaper than a new BCM2 (≈ PLN 2 200) [Elektroda, Anonymous, post #17540191]
12. How can I verify that coding succeeded?
Activate parking lights: EU mode shows outer tail + inner fog on left side. Scan module 09; it should report ‘No Faults Found’. Any 3157 bulb error means the fifth pin is still unpowered.
13. What is MIB2 and why was it mentioned?
MIB2 is Audi’s second-gen infotainment platform. Some users test VCP access to it while working on lamps, but lamp coding does not require MIB2 changes [Elektroda, Launch78, post #17538369]
14. Are there legal benefits to EU coding?
Yes. EU rear fog and dual brake light intensity comply with ECE R48 regulations, helping pass annual inspection and avoiding fines up to €200 in some EU states EU Road Safety Factsheet 2021.
15. What extra diagnostic functions does VCP offer after purchase?
Besides lamp coding, VCP handles adaptations, long-coding, and online parameter files for modules like ABS, Gateway, and Airbag on MQB and MLB-Evo platforms [Elektroda, Anonymous, post #17540195]
