Mercedes-Benz B17D349
The "Adaptive interior lighting" control unit for the rear center roof has malfunctioned. There is an internal electrical fault. • E48/5 (Adaptive rear interior lamp, roof, right)
Quick answer
DTC B17D349 indicates an internal electrical fault reported by the adaptive interior lighting control unit for the rear center roof. Verified applicability: 2022–2023 Mercedes-Benz EQS vehicles in the US.
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 B17D349 mean?
DTC B17D349 indicates an internal electrical fault reported by the adaptive interior lighting control unit for the rear center roof. Verified applicability: 2022–2023 Mercedes-Benz EQS vehicles in the US.
2. Technical explanation
Mercedes-Benz defines B17D349 as: “The ‘Adaptive interior lighting’ control unit for the rear center roof has malfunctioned. There is an internal electrical fault.” The diagnostic identifies E48/5, described in the supplied diagnostic record as the adaptive rear interior lamp, roof, right. The supplied official manufacturer communication also associates B17D349 with E48/4, the adaptive rear interior lamp, roof, center. This component-description inconsistency is present in the supplied evidence; its resolution is not yet established by verified evidence.
3. What system is affected?
Adaptive interior lighting; rear roof interior lamp/control unit.
4. How serious is this code?
Unknown. The supplied verified evidence does not assign a severity level.
5. Symptoms you may notice
- A B17D349 fault code may be stored in the rear interior lamp system. Further user-visible symptoms are not yet established by verified evidence.
6. Possible causes
- An internal electrical fault is identified by the DTC definition.
- The official manufacturer communication excerpt states that the cause involves software, but the supplied excerpt is truncated and does not provide the complete cause statement.
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
- Record the exact DTC and any observed rear interior-lighting behavior.
- Arrange diagnosis by an authorized Mercedes-Benz service provider, particularly if the code returns after clearing or is accompanied by lighting concerns.
- Do not attempt high-voltage or electrical control-unit repair procedures based on this information.
10. Step-by-step troubleshooting
- Confirm the stored DTC with a compatible diagnostic tool.
- Verify the vehicle identification number, model year, and US-market applicability before applying any manufacturer service guidance.
- Review Mercedes-Benz communication LI82.20-P-079313 through an authorized service provider. Specific diagnostic steps are not established by the supplied evidence.
11. When to contact service
Service need is listed as unknown in the supplied diagnostic record. However, an authorized Mercedes-Benz service provider can confirm the affected rear lamp/control-unit location and determine whether the applicable manufacturer communication applies.
12. What the service center may check
- Confirm whether B17D349 is stored in one or more rear interior lamps.
- Identify the applicable rear roof lamp/control unit using Mercedes-Benz vehicle-specific diagnostic information.
- Check for applicability of LI82.20-P-079313 to the vehicle. Additional service checks are not yet established by verified evidence.
13. Possible repair or resolution
- The supplied evidence does not establish a complete repair resolution.
- The cited official communication indicates a software-related cause in its provided excerpt, but the required corrective action is not included in the supplied evidence.
14. Affected vehicles
- Mercedes-Benz EQS · 2022–2023 · US
15. Related TSBs / service bulletins
- NHTSA Manufacturer Communication 11018613, Mercedes-Benz LI82.20-P-079313, published May 22, 2025. The supplied excerpt lists B17D349 among rear interior lamp fault codes and begins a cause statement referring to software. Full bulletin instructions were not supplied.
16. Recall information
- No recall information was supplied or established by verified evidence.
17. Official manufacturer information
Official source: NHTSA Manufacturer Communication 11018613 / Mercedes-Benz LI82.20-P-079313: https://static.nhtsa.gov/odi/ffdd/tsbs/TSBS_RECEIVED_2025-2026.zip#nhtsa_id=11018613
19. Frequently asked questions
What does Mercedes-Benz code B17D349 mean?
It means the adaptive interior lighting control unit for the rear center roof has malfunctioned and reports an internal electrical fault.
Which vehicles are verified as applicable?
The supplied applicability evidence identifies US-market 2022–2023 Mercedes-Benz EQS vehicles.
Is it safe to drive or charge with B17D349?
Driveability and charging safety are not yet established by verified evidence.
Is there a manufacturer communication for this code?
Yes. The supplied evidence cites Mercedes-Benz LI82.20-P-079313, filed with NHTSA as Manufacturer Communication 11018613.