Audi B16D5F4
left tail lamp 2 Turn signal light defective
Quick answer
For certain 2019–2020 Audi e-tron vehicles in the US, DTC B16D5F4 means “left tail lamp 2 Turn signal light defective.” Audi documentation identifies a tail-lamp software timing issue as the technical background when this code is stored with a rear turn-signal warning, even though the turn signals may remain functional.
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 B16D5F4 mean?
For certain 2019–2020 Audi e-tron vehicles in the US, DTC B16D5F4 means “left tail lamp 2 Turn signal light defective.” Audi documentation identifies a tail-lamp software timing issue as the technical background when this code is stored with a rear turn-signal warning, even though the turn signals may remain functional.
2. Technical explanation
Audi’s documented condition involves a left or right rear turn-signal warning in the instrument cluster while the turn signals remain functional. B16D5F4 may be stored in the comfort control module J393 (address word 0046). The cited Audi manufacturer communications identify a timing issue in tail-lamp software as the technical background. One communication states that new software in tail lamps MX3, MX4, and MX13 addressed the condition.
3. What system is affected?
Rear tail-lamp turn-signal function; comfort control module J393 (address word 0046).
4. How serious is this code?
Unknown. The verified evidence documents that the turn signals may remain functional, but it does not establish a severity classification.
5. Symptoms you may notice
- A left or right rear turn-signal warning may be displayed in the instrument cluster.
- The turn signals may remain functional.
- DTC B16D5F4 may be stored in comfort control module J393, address word 0046.
6. Possible causes
- A timing issue in the tail-lamp software is identified by Audi as the technical background for the documented condition.
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 rear turn-signal warning is displayed or B16D5F4 is stored.
- Do not assume the warning can be ignored merely because the turn signals may remain functional.
10. Step-by-step troubleshooting
- Verify whether a left or right rear turn-signal warning is displayed in the instrument cluster.
- Read fault memory in comfort control module J393 (address word 0046) and confirm whether B16D5F4 is stored.
- Have an Audi service provider determine whether the documented tail-lamp software condition applies.
11. When to contact service
Contact an Audi service provider for diagnosis and determination of applicable tail-lamp software action.
12. What the service center may check
- Check the instrument cluster for a rear turn-signal warning.
- Check comfort control module J393 (address word 0046) for B16D5F4.
- Assess applicability of the Audi tail-lamp software information described in the manufacturer communications.
13. Possible repair or resolution
- Audi documentation states that new software in tail lamps MX3, MX4, and MX13 addressed the documented condition.
- The exact repair procedure, vehicle eligibility, and software applicability are not fully established by the supplied evidence and should be confirmed by an Audi service provider.
14. Affected vehicles
- Audi e-tron · 2019–2020 · US
15. Related TSBs / service bulletins
- NHTSA Manufacturer Communication 10203693, Audi document A9421492062241_2, published 2021-11-19: identifies B16D5F4 among rear tail-lamp turn-signal DTCs and cites a tail-lamp software timing issue. https://static.nhtsa.gov/odi/tsbs/2021/MC-10203693-0001.pdf
- NHTSA Manufacturer Communication 10187587, Audi document A9421352062241_1, published 2021-02-23: identifies B16D5F4, cites a tail-lamp software timing issue, and states that new software in tail lamps MX3, MX4, and MX13 addressed the condition. https://static.nhtsa.gov/odi/tsbs/2021/MC-10187587-0001.pdf
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Verified applicability: Audi e-tron, model years 2019–2020, US region. The supplied official manufacturer communications were published through NHTSA and concern rear turn-signal warnings, B16D5F4 and related tail-lamp DTCs, and tail-lamp software timing.
19. Frequently asked questions
What does B16D5F4 mean?
It means “left tail lamp 2 Turn signal light defective.”
Can the turn signal still work with B16D5F4?
Yes. Audi’s documented condition states that the turn signals may remain functional while a left or right rear turn-signal warning is displayed.
What did Audi identify as the technical background?
Audi identified a timing issue in the tail-lamp software.
What resolution is mentioned in Audi documentation?
One supplied Audi manufacturer communication states that new software in tail lamps MX3, MX4, and MX13 addressed the condition.
Does this evidence prove the vehicle is safe to drive or charge?
No. Drive and charging safety are not yet established by the verified evidence supplied.