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Service bulletins for the 2021 Mercedes-Benz AMG GT

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

244 on file from NHTSA, as of 2026-10-19.

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Only bulletins with component: Electrical system are shown. Show all

Bulletins, newest first
LI82.85-P-0787222026-01-27. Service bulletin. ELECTRICAL SYSTEM. Complaint The vehicle's position on the map is displayed far away from its actual position, e.g. the vehicle is displayed as being in the middle of the ocean. Note: No relevant DTC is displayed during the quick test. Cause The GNSS antenna is not correctly inserted at the GNSS connection (see picture in the attachment) in the head unit (A26/17). Remedy Insert the plug into the GNSS connection and ensure that the plug has engaged correctly.
LI54.65-P-0801322025-12-15. Service bulletin. ELECTRICAL SYSTEM. Complaint 1. General Diagnostic Tips 2. One or More PARK Sensor Activations 3. Red Ring Around Vehicle 4. "Active Parking and Parking Assist Inoperative" on Instrument Cluster 5. Cameras 6. Other Park Topics Cause Various root causes Remedy See attached diagnostic guide.
LI54.30-P-0800902025-12-09. Service bulletin. ELECTRICAL SYSTEM. Complaint The Head-up display (HUD) may be perceived as too bright and without adjustment. Cause Signal from the rain/light sensor is not recognized/processed correctly. As a result, the HUD is permanently displayed at maximum brightness. The customer has the option to turn off the HUD via MBUX. Remedy Software update of the "Head-up display" control unit.
NCU - 20240900072025-10-10. Service campaign. ELECTRICAL SYSTEM. Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain subject vehicles, the engine control unit software does not correspond to current production specifications. As a consequence, the functionality of the post-catalyst oxygen sensor may be impaired due to increased thermal loading. MBUSA will conduct a service campaign. An authorized Mercedes-Benz dealer will update the engine control unit software.
LI54.10-P-0696982025-09-22. Service bulletin. ELECTRICAL SYSTEM. See Attachment
LI54.10-P-0797722025-09-18. Service bulletin. ELECTRICAL SYSTEM. Complaint After a software update from campaign 2025050001 of component LIB48_222 - G1/3 (48 V on-board electrical system battery) from software release A 000 902 50 48 to software release A 000 902 15 89, the fault code B183319 may be output. B183319 "The battery for the 48V on-board electrical system has a malfunction. The limit value for current has been exceeded" Cause Anomaly in the software update Remedy Please perform the following steps in the specified sequence: 1.) Delete fault codes 2.) Disconnect XENTRY Diagnosis and the 12 V battery charger 3.) Disconnect ground cable from the 12 V battery 4.) Ensure bus idle for at least 10 minutes 5.) Re-connect ground cable to the 12 V battery 6.) Delete fault codes again 7.) Perform a test drive 8.) Check fault codes > If fault code B183319 is still current, continue with the guided fault analysis in XENTRY Diagnosis. > If fault code B183319 goes to stored and can be cleared, no further action is required.
NCU - 20250800072025-09-12. Service campaign. ELECTRICAL SYSTEM. Issue Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain subject vehicles, the High Voltage Battery (“HVB”) AC charger software does not correspond to current production specifications. As a consequence, a HVB MIL may illuminate during charging due to fluctuations in power consumption of the charging socket actuator. Remedy MBUSA will conduct a service campaign. An authorized Mercedes-Benz dealer will update the HVB AC Charger Software.
LI54.10-P-0797722025-09-12. Service bulletin. ELECTRICAL SYSTEM. Complaint After a software update of component LIB48_222 - G1/3 (48 V on-board electrical system battery) from software release A 000 902 50 48 to software release A 000 902 15 89, the fault code B183319 may be output. B183319 "The battery for the 48V on-board electrical system has a malfunction. The limit value for current has been exceeded" Cause Anomaly in the software update Remedy Please perform the following steps in the specified sequence: 1.) Delete fault codes 2.) Disconnect XENTRY Diagnosis and the 12 V battery charger 3.) Disconnect ground cable from the 12 V battery 4.) Ensure bus idle for at least 10 minutes 5.) Re-connect ground cable to the 12 V battery 6.) Delete fault codes again 7.) Perform a test drive 8.) Check fault codes > If fault code B183319 is still current, continue with the guided fault analysis in XENTRY Diagnosis. > If fault code B183319 goes to stored and can be cleared, no further action is required.
LI46.10-P-0780122025-08-01. Service bulletin. LANE DEPARTURE: ASSIST; ELECTRICAL SYSTEM; FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL. Complaint Hand detection system not operating correctly / vehicles with code 266 Fault message in instrument cluster: "Active Emergency Stop Assist not available" "Active Lane Keeping Assist not available" Cause Possible causes: the hand detection mat, the hand detection control unit, the contacts and the steering wheel harness. Remedy In the event of a customer complaint and fault code in IDC control unit: U186B29 in IDC223 or fault code U0429E0, U042941, U042929, U042902, U0429E1 in IDC213 or fault code in HOSWD control unit: B1E7614 Test: Please perform the new SCN coding for HOSWD control unit (N179/1) (available since May 2025). Please flash the IDC (N62/4) software A223 902 75 37 (only applies to HOSWD223). Erase fault memory Remedy: Switch on ignition without touching the steering wheel. If after 10 seconds without touching the steering wheel, one of the two fault messages appears in the IC: Please check contacts and feed lines in the steering wheel by means of visual inspection for damage, crimped connections, loose connections, etc. (example in picture 2 and 3). If there is visible damage -> replace steering wheel electronics or feed lines. If there is no visible damage -> Proceed to replace the steering wheel. If no yellow message appears in the instrument cluster within 10 seconds: Please grab the steering wheel all the way round, including the 6 o'clock chrome molding, with both hands (see picture 1). If the fault is triggered by grabbing the steering wheel rim or pressing on the 6 o'clock clasp, check contacts and feed lines in the steering wheel by means of visual inspection for damage, crimped connections, loose connections, etc. (example in picture 2 and 3). Check ground connections (screw connections and cable to steering wheel rim); if necessary tighten screws/bolts and check for corrosion (Picture 4). If there is visible damage -> replace steering wheel electronics or feed lines. If no fault is visible -> Proceed to replace the steering wheel. In the event of a customer complaint and further fault code in HOSWD: B1E7713: Check ground connections (screw connections and cable to steering wheel rim); if necessary tighten screws/bolts and check for corrosion (Picture 4). B1F1F04: Check hand detection system control unit; if necessary swap with donor vehicle (ensure that the HW part numbers are identical).
OTA - 202507252025-07-29. Over-the-air update. LANE DEPARTURE: ASSIST; ELECTRICAL SYSTEM; FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL; LANE DEPARTURE: WARNING. Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has updated driver assistance system software available for certain subject vehicles. The updated software improves system stability and enhances the robustness of the driver assistance system. MBUSA will conduct an OTA service campaign. Remote software updates are automatically downloaded and installed in the customer’s vehicle free of charge and do not require a dealer visit.
NCU - 20250700022025-07-29. Service campaign. ELECTRICAL SYSTEM. Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain subject vehicles, the 48V battery control unit software might not meet current production specifications. In rare cases, the engine malfunction indicator lamp might not illuminate when a diagnostic fault condition is present. MBUSA will conduct a service campaign. An authorized Mercedes-Benz dealer will update the 48V battery control unit software on affected vehicles. Affected customers will be notified via in-vehicle notification or First-Class letter to have the update performed on their vehicle.
NCU - 20250700032025-07-24. Service campaign. ELECTRICAL SYSTEM. Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain subject vehicles, the 48V battery control unit software might not meet current production specifications. In rare cases, the engine malfunction indicator lamp might not illuminate when a diagnostic fault condition is present. MBUSA will conduct a service campaign. An authorized Mercedes-Benz dealer will update the 48V battery control unit software on affected vehicles. Affected customers will be notified via in-vehicle notification or First-Class letter to have the update performed on their vehicle.
OTA - 202506272025-06-27. Over-the-air update. LANE DEPARTURE: ASSIST; LANE DEPARTURE: WARNING; FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL; ELECTRICAL SYSTEM. Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has updated driver assistance system SCN coding available for certain subject vehicles. The updated SCN coding improves system stability and enhances the availability of driver assistance features. MBUSA will conduct an OTA service campaign. Remote SCN coding updates are automatically downloaded and installed in the customer’s vehicle free of charge and do not require a dealer visit.
CL - 050120252025-06-03. Other. ELECTRICAL SYSTEM; FUEL/PROPULSION SYSTEM. In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfaction of our customers, Mercedes-Benz USA is extending the warranty coverage for the Diagnostic Module for Tank Leakage detection (“DMTL”) on your vehicle from the original New Vehicle Limited Warranty of 4 years / 50,000 miles to 15 years/150,000 miles (whichever occurs first). This applies to the vehicle regardless of ownership.
LI54.71-P-0788022025-05-30. Service bulletin. ELECTRICAL SYSTEM. Complaint MBUX head unit display with red text box "System Inoperative". ONLY for vehicles with SA code (549+21U) or (549+U19). Cause Head unit software variant. Remedy For all chassis use Xentry to update head unit (A26/17). Target boot software number should be either: • 247 904 6600 (E905.4) OR • 247 904 7500 (E906.1) If vehicle fits all criteria and either target software is not available via Xentry, please open an XSS ticket. Damage code 5424x-01 may be used with a repair start date after June 2nd, 2025.
LI54.21-P-0793692025-05-30. Service bulletin. ENGINE; ELECTRICAL SYSTEM. Complaint The customer complains that there is a humming/droning/throbbing/ear pressure in the interior at low engine speeds (up to 2400 rpm). Cause In the current software state, the EOC system (Active Noise Cancellation), which reduces the humming in the interior, fails permanently, without a DTC (Diagnostic Trouble Code) being stored. Remedy Remedy software available in Xentry: • Vehicles with code 810: SW update ASX (N156/1) and SND (N40/3) control unit • Vehicles with code 811: SW update ASX (N156/1) and SND (N40/3) control unit After the ASX & SND software update, initial start up of the control units must be performed.
LI82.85-P-0792712025-05-29. Service bulletin. ELECTRICAL SYSTEM. Complaint After a software update of HERMES communication module N112/9 has been performed on a gray import vehicle, the message "SOS - Service not activated" is displayed in the instrument cluster. Cause The message "SOS - Service not activated" tells the customer that "over-the-air" registration of the vehicle with the Mercedes Intelligent Cloud is not possible. On a gray import vehicle, this is due to the fact that the SIM card installed in the HERMES communications module cannot dial into the mobile phone network in the importing country. Remedy The only way of avoiding the message in the instrument cluster is to deactivate the HERMES module using the 09o deactivation process after obtaining the customer's consent. After deactivation, the HERMES control unit (N112/9) has the operating status "Inoperative". The message "SOS not ready" appears in the audio/COMAND display (A40/8) and may also appear in the instrument cluster. This display message tells the customer that the emergency call function is not available. In addition, the workshop must attach a label (2 x part number A9078172900 required) to the cover of the emergency call button in the overhead control panel and to the emergency call button itself. Replacing the hardware of the HERMES communication module is not effective.
NCU-20250500012025-05-09. Emissions. ELECTRICAL SYSTEM. Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that certain Model Year (“MY”) 2019 – 2022 C-Class, CLS, E-Class, E-Class Coupe/Convertible, GLE/GLS-Class and AMG GT vehicles (206, 257, 213, 238,167 and 290 platforms) are potentially affected with multiple topics related to the 48V battery management system, which erroneously may or may not illuminate the check engine malfunction indicator lamp (‘MIL’) in one or more of the following circumstances: • Memory error causing battery switch to open, prohibiting vehicle to restart; • The battery thermal management system, power supply voltage (12V) measurement and 48V battery switch diagnostic may not be monitored by the OBD-system; • Plausibility check of the temperature sensor, temperature range and Real Time Clock (RTC) monitoring might not operate as intended. MBUSA will conduct an Emission Service Campaign. An authorized Mercedes-Benz dealer will update the drivetrain control unit software on the affected vehicles. Affected customers will be notified via First Class letter to have the update performed on their vehicle.
LI82.85-P-0783032025-05-06. Service bulletin. ELECTRICAL SYSTEM. Complaint Individual functions such as sliding sunroof or roller sunblind can no longer be operated using the gesture recognition system. Cause Gesture recognition system control unit software N168 Remedy For vehicles before modification year 23/2: Perform SCN coding in control unit OMSH223 (N168). For vehicles as of modification year 23/2: Considered to be a series production configuration. A change will not be possible in future. NOTE: The information contained in this document is intended for use by trained, professional technicians with the knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of vehicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes resulting in the same or similar symptoms or conditions described in this document, and trained professional service technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained in this document does not guarantee warranty coverage nor does it extend the vehicle’s warranty in any way.
LI54.71-P-0788022025-04-01. Service bulletin. ELECTRICAL SYSTEM. Complaint MBUX head unit display with red text box "System Inoperative". ONLY for vehicles with SA code (549+21U) or (549+U19). Cause Head unit software variant. Remedy For all chassis use Xentry to update head unit (A26/17). Target boot software number should be either: • 247 904 6600 (E905.4) OR • 247 904 7500 (E906.1) If vehicle fits all criteria and either target software is not available via Xentry, please open an XSS ticket.
OTA - 54977482025-03-17. Over-the-air update. ELECTRICAL SYSTEM. Issue Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain subject vehicles, the communication software does not correspond with the latest series production configuration. The communication module will receive an OTA update which includes quality-enhancing optimizations and improves the system stability and accessibility of Mercedes me services. The update is downloaded and installed in the background. During installation, the system can be used without restrictions. The new software will become active after the vehicle has been restarted. Remedy MBUSA will conduct an OTA service campaign. Remote software updates are automatically downloaded and installed in the customer’s vehicle free of charge and do not require a dealer visit.
OTA - 54977462025-03-17. Over-the-air update. ELECTRICAL SYSTEM. Issue Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain subject vehicles, the communication software does not correspond with the latest series production configuration. The communication module will receive an OTA update which includes quality-enhancing optimizations and improves the system stability and accessibility of Mercedes me services. The update is downloaded and installed in the background. During installation, the system can be used without restrictions. The new software will become active after the vehicle has been restarted. Remedy MBUSA will conduct an OTA service campaign. Remote software updates are automatically downloaded and installed in the customer’s vehicle free of charge and do not require a dealer visit.
LI82.70-P-0774332025-03-17. Service bulletin. ELECTRICAL SYSTEM. Complaint During a phone call, the called party has difficulty understanding/cannot understand the driver, or interference/background noises are audible to the called party during a call. It becomes increasingly difficult to understand as the speed rises. Cause A. Seating of the microphones in the headliner. Side edges are covered by the textile cover (see picture "1") B. Assembly of microphones (B25/20 or B25/21) in the headliner. C. Dirt inside the microphone housing Remedy 1. Press finger on rear of microphone (on adhesive tape) 2. Remove microphone cap from the front 3. Eliminate protruding material residues of the microphone cutout at the headliner, e.g. with a soldering iron. The microphone must be seated in the headliner as shown in picture "2". 4. Push microphone from behind until it is firmly pressed into the headliner 5. Maintain pressure and press/clip cap into microphone from the front. Note: The cover cap must be clearly heard and felt to engage. 6. This procedure must be carried out on both microphones (B25/20 and B25/21) Note: • It is recommended to replace the cover caps. • The non-woven cloth in the cover cap protects the microphone from soiling and must not be removed. NOTE: The information contained in this document is intended for use by trained, professional technicians with the knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of vehicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes resulting in the same or similar symptoms or conditions described in this document, and trained professional service technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained in this document does not guarantee warranty coverage nor does it extend the vehicle’s warranty in any way.
OTA- 24P54977472025-02-28. Over-the-air update. ELECTRICAL SYSTEM. Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain MY19-25 A-Class, C-Class, CLA, CLS, E-Class, G-Class, GLA, GLB, GLC, GT, and S-Class (118, 177, 205, 213, 217, 222, 238, 247, 253, 257, 290, 463 platform) vehicles, the communication software does not correspond with the latest series production configuration. The communication module will receive an OTA update which includes quality-enhancing optimizations and improves the system stability and accessibility of Mercedes me services. The update is downloaded and installed in the background. During installation, the system can be used without restrictions. The new software will become active after the vehicle has been restarted. MBUSA will conduct an OTA service campaign. Remote software updates are automatically downloaded and installed in the customer’s vehicle free of charge and do not require a dealer visit. No customer letter will be mailed for this OTA software update. Parts Parts are not required
OTA - 24P54977452025-02-28. Over-the-air update. ELECTRICAL SYSTEM. Mercedes-Benz AG, the manufacturer of Mercedes-Benz vehicles, has determined that on certain MY20-25 A-Class, C-Class, CLA, CLS, E-Class, EQB, GLB, GLE, GLS, AMG GT 4-Door, and S-Class (118, 167, 177, 205, 213, 222, 238, 243, 247, 257, 290 platform) vehicles, the communication software does not correspond with the latest series production configuration. The communication module will receive an OTA update which includes quality-enhancing optimizations and improves the system stability and accessibility of Mercedes me services. The update is downloaded and installed in the background. During installation, the system can be used without restrictions. The new software will become active after the vehicle has been restarted. MBUSA will conduct an OTA service campaign. Remote software updates are automatically downloaded and installed in the customer’s vehicle free of charge and do not require a dealer visit. No customer letter will be mailed for this OTA software update.

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.