2021 Mercedes-Benz CLS 450

During a trip driving from Sedona to San Diego, the rear passenger side rim (Part No. 25740120007x23) (see Picture1) failed with a through crack on the shoulder opposite the spoke side (see Picture2). This led to the loss of air pressure in the tire. The tire pressure sensor did indicate a low pressure condition. Upon inspection of the rim, the only possible solution was to have it welded in order to continue the trip. When the rim was taken to the repair shop, three more cracks were discovered on the rim inner surface. None of these three cracks have not gone through the rim wall yet. All crack were on the shoulder opposite the spoke side which cantilevers towards the center of the car. Welded cracks are shown in Picture3 through Picture6. Picture 3 shows the weldment of the crack that went through the rim wall. This cracks developed during normal driving conditions and were not the result of impacts. They could have resulted in a catastrophic failure that might have resulted in loss of control of the car and a potentially serious accident. I had the welded rim replaced by a new one at the Mercedes Benz Service Center in Ontario, CA. The service center retained the welded rim.

NHTSA ID

11472277

Incident

Jun 30, 2022

This NCU replaces the prior NCU issued on May 15, 2025, and contains additional MY 2023 and MY 2024 vehicles which are highlighted below. In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfaction of our customers, Mercedes-Benz USA, LLC (“MBUSA”) is extending the warranty coverage on the Diagnostic Module for Tank Leakage detection (DMTL) in certain Model Year (“MY”) vehicles listed below from the original New Vehicle Limited Warranty of 4 years/50,000 miles to 10 years/120,000 miles (vehicles certified as LEV II) and 15 years/150,000 miles (vehicles certified as LEV III), whichever occurs first, for the following condition: •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’).

Complaint Hand detection system – malfunction / vehicles with code 266 Fault message in instrument cluster: "Active Emergency Stop Assist not available" "Active Lane Keeping Assist not available" "Active steering assist not available" Cause Possible causes: Hand detection mat, hand detection control unit, contacts, and electrical feed line. 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 Check: Please do not replace the HOSWD control unit. Please flash the new SW and perform the SCN coding for the HOSWD control unit (N179/1) (available from July 2026). The software can be flashed onto all HOSWD213 with HW number A0009011522 and all HOSWD223 with HW number A0009011422. Please also flash the SW for the IDC control unit (N62/4), if possible (only applies to HOSWD223). Erase fault memory Remedy: Turn on the ignition or start the engine without touching the steering wheel. If, after 10 seconds without touching the steering wheel, one of the three fault messages appears on the instrument cluster: Check the contacts and feed lines in the steering wheel by means of a visual inspection for damage, crimp connections, loose connections, etc. (example in picture 2 and 3). If there is visible damage -> replace the steering wheel electronics or the feed lines. If there is not any visible damage -> replace the steering wheel rim. If a yellow message does not appear on the instrument cluster within 10 seconds: Grasp the steering wheel fully with both hands, including the chrome molding at the 6 o'clock position (see picture 1). If the fault is triggered by grasping the steering wheel rim or pressing the clip at the 6 o'clock position, check the contacts and feed lines in the steering wheel by means of a visual inspection for damage, kinked connections, loose connections, etc. (example in picture 2 and 3). Check the ground connections (screw connections and cables to the steering wheel rim); if necessary, retighten the screws/bolts and check for corrosion (picture 4). If there is visible damage -> replace the steering wheel electronics or the feed lines. If there is not any visible damage: Replace the steering wheel rim. Please do not replace the HOSWD control unit. A TIPS case should be created if fault profile is unclear. In the event of a customer complaint and a further fault code in HOSWD: B1E7713: Check the ground connections (screw connections and cables to the steering wheel rim); if necessary, retighten the screws/bolts and check for corrosion (picture 4). B1F1F04: Check the control unit of the hand detection system; if necessary, replace this with the control unit from a donor vehicle (make sure that the hardware part numbers are identical).

Single throttle lift-off clunking noise from the side shaft when moving off (audible at the outboard end). The noise is heard once in each instance when changing direction of travel. Note: Sound file in attachment Cause If the complaint is eliminated by experimentally loosening the outboard collar nut (by 1 turn), the problem is due to cracking of the microweld between the wheel bearing inner race and the joint housing of the side shaft. Note: The collar nut must always be replaced after being loosened. See also LI33.20-P-078406 Remedy Coat contact surface of side shaft with wheel bearing with Molykote paint. To do this, proceed as follows: 1. Remove side shafts 2. Clean contact surface A (see image file in attachment "Outer joint housing before") before coating with Molykote, using "spirit" (free of dust and grease) 3. Coat contact surface A (see image file in attachment "Outer joint housing after") with Molykote and leave to dry for "one hour" in removed condition 4. Reinstall side shafts Note: Before using the antifriction coating (Molykote), stir it or shake it thoroughly for (at least 1 minute).

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, July 9, 2026. After July 9th, 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.

Complaint Service code B1 displayed in the customer menu does not match the workshop code displayed in the workshop menu, e.g., 505 or 550A, which includes a service A. Cause The root cause is currently being investigated. Remedy To determine the cause, the instrument cluster control unit (N133/1) and powertrain control unit (N127) logs are required before confirming the service or correction using XENTRY Diagnosis. Please open a TIPS case to BCE inbox with the requested information in the attachments.

Complaint After successful commissioning of the HERMES control unit (N112/9) with XENTRY Diagnosis DVD 03/2026, the message "SOS - service not activated" appears on the instrument cluster. In addition, the following two conditions are also met: • HERMES (N112/9) control unit: event code B15CE00 is ACTIVE and STORED (A+S) • Vehicle Documentation System: For the HERMES control unit, the EID1, EID2, ICCID, IMEI, IMSI, TELNR fields in the "Identification/Serial number" column have the value "-" Cause Still under analysis Remedy Recommission the HERMES control unit (N112/9) with XENTRY Diagnosis 03/2026 and add-on 33399 installed or carry out the procedure with a newer version of XENTRY Diagnosis: XENTRY→ "N112/9 - Control unit for telematics services (HERMES)" -> "Adaptations" -> "Control unit commissioning" -> "Commissioning of previously installed control unit"