2023 Mercedes-Benz AMG C43

My vehicle developed a coolant warning during normal road use. I had not experienced any known collision, crash, or unusual impact. I brought the vehicle to an authorized Mercedes-Benz dealer for inspection. The dealer diagnosed the problem as: “Front low-temperature cooler replacement – impact damage causing leak.” The repair estimate was approximately $2,385. The failed component is the front low-temperature cooler located directly behind the lower front grille. Based on the location and design, the cooler appears to have limited protection from ordinary road debris. The dealer believes that external impact caused the cooler to leak. I am concerned that this may represent a design or durability issue because a critical cooling-system component appears vulnerable to relatively small road debris during normal driving. A puncture or leak in this component can result in coolant loss, warning messages, overheating, reduced vehicle operation, or potentially loss of propulsion if the vehicle continues to be driven before the driver realizes the severity of the leak. This is a significant safety concern because the failure can occur suddenly during normal highway or road use without a collision. A driver may be forced to stop unexpectedly or may continue driving with insufficient coolant, which could create a risk to the driver and other road users. I believe Mercedes-Benz should review whether the front low-temperature cooler has adequate protection from normal road debris and whether additional protective screening, grille protection, or a revised component design is needed. The issue has been confirmed by an authorized Mercedes-Benz dealer. The vehicle and damaged component should be available for inspection if requested. I am requesting that NHTSA review whether similar complaints exist and whether this condition may represent a broader safety-related design concern.

NHTSA ID

11766731

Incident

Sep 23, 2026

I am filing a safety complaint regarding my 2023 Mercedes-Benz AMG C43 4MATIC. The vehicle has approximately 23,000 miles. On multiple occasions, the vehicle has abruptly and violently applied the brakes and/or come to a near stop while I was driving on highways and side roads, even though there was nothing in front of me that should have triggered emergency braking. There was no vehicle, pedestrian, cyclist, object, or road hazard present that would justify this braking event. This is not normal braking behavior. The car essentially performs an uncommanded emergency stop or severe deceleration without warning. The force is strong enough to create a serious risk of being rear-ended by vehicles behind me. This has happened at highway speeds and on local roads, making the vehicle unsafe to operate. If a following driver is unable to react in time, this defect could easily cause a crash, injury, or death. The problem appears related to the vehicle’s automatic emergency braking / Active Brake Assist / forward collision avoidance system and possibly other linked driver-assistance systems. The vehicle has already been serviced on two separate occasions for this exact issue, yet the problem has occurred again. Despite bringing the vehicle in for repair more than once, the defect remains unresolved. Because this dangerous unintended braking continues to happen, I cannot continue to drive the car safely with this issue unresolved. On April 1, 2025, I took the vehicle to Aristocrat Motors in Merriam, Kansas for the car slamming on the brakes and beeping when no one was around. The service center calibrated the augmented reality camera and performed a test drive. The invoice indicates that they were unable to duplicate the braking event during the test drive. They ran codes with SDS and found that the augmented reality camera was not calibrated correctly, so they performed a calibration. On December 31, 2025, I again took the vehicle to Aristocrat Motors in Merriam, Kansa

NHTSA ID

11735812

Incident

May 5, 2026

The contact owns a 2023 Mercedes-Benz C43 AMG. While driving into a parking lot at a very slow speed, the braking system suddenly activated, and the vehicle shut off. After restarting the vehicle, the messages "Rear Axle Malfunction", "Active Braking System Limited" and "Inoperative" were displayed. The cause of the failure was not yet determined. The manufacturer and local dealer were notified of the failure. The failure mileage was 5,600.

NHTSA ID

11572056

Incident

Feb 15, 2024

Mileage

5,600 mi

Complaint During part of the steering movement, it feels heavier or more difficult to steer in the same spot every time. OR Rattling, humming, dry sliding/gravel noise from the electric steering system when steering (see attachment). Complaint does not impact the ability to safely steer or control the vehicle. Cause Ball screw drive (KGT) of electric steering damaged by: 1. External force due to: ‑ Hitting the curb/posts with the front wheels. ‑ Driving over obstacles (e.g. pothole/ threshold/ speed bump/ gully) at an inappropriate speed. 2. Corrosion/ water ingress through a damaged boot (see attachment). ‑ Cracks (1) ‑ High pressure cleaner (2) ‑ Animal bite (3) See various examples listed in the attachments for examples of outside influence. Remedy Remove boot clamps closest to steering gear housing on both left and right (as seen in "Steering Rack Boot Clamp Location"). Pull back boot and inspect for rust, broken end stops, water, or any other anomalies. Replace electric steering. Note: Steering gears replaced due to outside influence or damage must not be claimed under warranty!

Complaint • Harsh 1‑2, 2‑3, and/or 3‑4 shift • Jerky shifting • Jolting when accelerating from stop Cause Insufficient software application causing elevated K81/K27/B05 fill time adaptations and elevated torque adaptations for concerning shift. Note: Shift quality in E Performance models can be affected if the HV Battery state of charge (SOC) reaches 25% or below. Remedy Check VGS software level, and follow relevant remedy instructions. (see attachment) AMG 43 models with VGS software levels up to 22A: As of 4/18/2025, an aftersales software improvement has been released. This software has been implemented in production as of model year 2024, however this LI should still be followed if the concern is present. 232 ‑ A0009025699 206 ‑ A0009025599 Please ensure your Xentry machine is up to date with the latest Add Ons and continue with the following steps: Note: ALL steps must be performed to rectify concern 1. Perform software update all control units included in VGS software update. 2. Check transmission oil level and correct, if necessary (transmission oil temperature > 60 °C) 3. Perform Xentry Valve Flushing procedure at least 3x 4. Perform resetting of deceleration values (VGS > Special Procedures > Special procedure > Resetting learned values Deceleration mode) 5. Perform a standstill adaptation, then read out new EEPROM data 6. Perform driving adaptation(s) while adhering to the below parameters for at least 20‑30 miles. Note: There is no menu in Xentry for this procedure. We recommend displaying the torque in the instrument cluster. If all below parameters are met at the time the shift, a driving adaptation will automatically occur. Harsh 1‑2 Perform a driving adaptation of 4‑5 (adapts K81 for the 1‑2 shift) Harsh 2‑3 Perform a driving adaptation of 6‑7 (adapts B05 for the 2‑3 shift) Harsh 3‑4 Perform a driving adaptation of 3‑4 (adapts K27 directly) ‑ See attached PDF for min/max torque, and RPM parameters ‑ Transmission oil temperature > 30°C (>86°F) ‑ Level track (no incline/decline) ‑ Slippery drive program ‑ Display the torque in the instrument cluster ‑ Constant engine torque ‑ Do not shift via paddle AMG 63 models with VGS software levels up to 22A: No aftersales software resolution is planned. Perform above steps and release the vehicle. If the vehicle returns and already had ALL steps in this LI performed on a previous visit, or has software level 23A and newer: Please submit a TIPS case to the Powertrain inbox and ensure the following is included: ‑ Initial Quick Test w/ Freeze Frame Data ‑ VGS Control Unit Log ‑ Initial EEPROM (before any adaptations or Xentry procedures were performed) ‑ Detailed vehicle history of the complaint

Complaint Tailgate opens unintentionally. Cause Accidental or unnoticed activation of the button to open the tailgate on the vehicle key. EXAMPLE: when stored in trouser pocket, handbag etc. Remedy As of the 6th generation, the vehicle key can be recoded so that the tailgate no longer opens as a result of a long press on the button, but by double‑clicking on the button instead. This reduces the likelihood of the button being activated accidentally or unintentionally. The recoding can be carried out as follows: 1. Add SA Code O19 into VeDoc (O for Oscar, not "zero") • an XSS ticket may be necessary to add the SA code 2. Perform SCN coding of EIS N73 control unit 3. Deactivate the vehicle key (a successful deactivation is indicated by the LED lighting up 2x briefly and then 1x for a long period). 4. Place the vehicle key in the storage compartment on the key symbol and turn on the ignition. IMPORTANT: all other vehicle keys must be outside the recognition range of the vehicle when doing this! Perform steps 3 and 4 successively for all vehicle keys. Notes: 6th, 7th and 8th generation keys can be deactivated as follows: Up to modification year 22/1 by double clicking the "Lock button" As of modification year 22/1, by press and holding the “Lock button", then double‑click the “Unlock button" at the same time. On model series 167, the storage compartment with the key symbol is located in the armrest. The SCN coding from the EZS is only transferred correctly to the vehicle key under the following conditions: Only one vehicle key is located in the vehicle, this key has been deactivated and it is positioned on the marking in the storage compartment for the data transfer. The costs for this adaptation are to be borne by the customer. For the newer BR 174, 178, 244, 248, 520, and 540, a software update must be initiated, as there is no way to perform SCN coding.

Complaint Traffic sign symbol for "Traffic Sign Assist" is blinking in instrument cluster without obvious cause usually with one of the following scenarios: • Flashing without a speed limit ("‑ ‑"). • Flashing when current vehicle speed is under speed limit. • Flashing between US speed limit symbol and European speed limit symbol. NOTE: • Verify that the concern falls under one of the attachment videos. If not, then it is outside of the scope of this LI. • This also does not cover "Traffic Sign Inoperative" messages on the instrument cluster. Cause There are two identified reasons for this concern: 1. Country code information stored incorrectly at a particular geographic latitude range. 2. Incorrect reference data when the vehicle is started and a GPS signal is not immediately available. Remedy Update head unit software to latest version and the re‑check function in the same location. If vehicle is still exhibiting one of the symptoms as described exactly as in the complaint section or as shown in the video attachments, open a TIPS case to the Body/Chassis/Entertainment inbox with the following: • Video of the concern. • Exact location (latitude and longitude is best)

Dear Mercedes-Benz Owner: 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. Why the Warranty extension? On certain Model Year 2018 - 2024 A / C / CLA / CLS / E / G / GLA / GLB / GLC / GLE / GLS / GT / S / SL Mercedes-Benz vehicles, under certain circumstances, the DMTL may trigger erroneous Diagnostic Trouble Code ("DTC") entries that may result in the illumination of the Check Engine Malfunction Indicator Lamp ("MIL"). Any repairs under this warranty extension must be performed by an authorized Mercedes-Benz dealership. • If your preferred authorized Mercedes-Benz dealership performs a diagnosis and confirms that your vehicle has the issue, the repair will be covered under this extended warranty and performed at no cost to you. • This extended warranty does not apply to any other components or conditions beyond the ones mentioned above, and standard warranty terms apply, including the exclusions with respect to extra expenses, as identified in the Service and Warranty Information booklet.

Dear Mercedes-Benz USA Dealers, The part numbers listed in the chart below should no longer be installed, and any existing stock must be returned to your facing PDC. The deadline for all dealer returns is no later than Thursday, September 3rd, 2026. After September 3rd, returns of these parts will no longer be accepted. These parts should be returned via ZSR Special Return, using item category SCM Authorized Part Return. Please include a copy of this NCU as your authorization to return these parts. This procedure will not affect your return allowance. All returned parts will be replaced in accordance with the chart provided below.