Audi B16D431
Left tail lamp 1, no signal/open circuit
Quick answer
For certain 2020–2021 Audi e-tron vehicles in the US, DTC B16D431 identifies “Left tail lamp 1, no signal/open circuit.” Audi’s published service information attributes this condition to tail-lamp diagnostic software that is too sensitive and states that updated software is available.
This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.
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1. What does B16D431 mean?
For certain 2020–2021 Audi e-tron vehicles in the US, DTC B16D431 identifies “Left tail lamp 1, no signal/open circuit.” Audi’s published service information attributes this condition to tail-lamp diagnostic software that is too sensitive and states that updated software is available.
2. Technical explanation
The verified manufacturer communication says B16D431 may be stored in the comfort system central control module, J393 (address word 0046). The communication identifies the code as Left tail lamp 1, no signal/open circuit. Its stated technical background is that the diagnostic software in the tail lamps is too sensitive; the stated production solution is updated software.
3. What system is affected?
Left tail lamp 1 and the comfort system central control module J393 (address word 0046).
4. How serious is this code?
Not yet established by verified evidence.
5. Symptoms you may notice
- A tail lamp warning may be displayed in the instrument cluster.
- The instrument-cluster turn-signal indicator may flash rapidly when the turn signal is activated.
6. Possible causes
- Audi’s service communication states that tail-lamp diagnostic software is too sensitive.
7. Can I still drive the vehicle?
Not yet established by verified evidence.
8. Can I charge the vehicle?
Not yet established by verified evidence.
9. What you can safely do
- Arrange diagnosis by an Audi service provider if a tail-lamp warning is displayed or B16D431 is stored.
- Do not attempt electrical or lamp-control-module repair based on this information alone.
10. Step-by-step troubleshooting
- A workshop can confirm whether B16D431 is stored in comfort system central control module J393, address word 0046.
- A workshop can assess applicability of the Audi software update described in the manufacturer communication.
11. When to contact service
Contact an Audi service provider for diagnosis and to determine whether the applicable tail-lamp software update is available for the vehicle.
12. What the service center may check
- Check the comfort system central control module J393 (address word 0046) for DTC B16D431.
- Review the tail-lamp warning and rapid turn-signal indicator behavior described in the manufacturer communication.
- Determine whether updated tail-lamp software applies.
13. Possible repair or resolution
- Audi’s manufacturer communication states that updated tail-lamp software is available.
- The exact repair outcome for an individual vehicle is not yet established by verified evidence.
14. Affected vehicles
- Audi e-tron · 2020–2021 · US
15. Related TSBs / service bulletins
- NHTSA Manufacturer Communication PDF 10199220: A9421422063973_1, published July 14, 2021. It covers a tail-lamp warning/rapid turn-signal-indicator condition and lists B16D431 among possible stored DTCs. The communication states that tail-lamp diagnostic software is too sensitive and that updated software is available: https://static.nhtsa.gov/odi/tsbs/2021/MC-10199220-0001.pdf
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Verified applicability: Audi e-tron, model years 2020–2021, US region. Official source: NHTSA-hosted Audi manufacturer communication 10199220, published July 14, 2021: https://static.nhtsa.gov/odi/tsbs/2021/MC-10199220-0001.pdf
19. Frequently asked questions
What does Audi code B16D431 mean?
It means “Left tail lamp 1, no signal/open circuit.”
What symptoms are documented for this condition?
The official communication documents a tail-lamp warning in the instrument cluster and possible rapid flashing of the instrument-cluster turn-signal indicator when the turn signal is activated.
What does Audi identify as the technical background?
Audi states that diagnostic software in the tail lamps is too sensitive.
Is there an available service solution?
The manufacturer communication states that updated software is available.
Does this information confirm the vehicle is safe to drive or charge?
No. Driveability and charging safety are not yet established by verified evidence.