2015 Mercedes-Benz C 300

From 2000 through 2017, Takata produced millions of air bag inflators using two types of phase-stabilized ammonium nitrate ("PSAN") propellant -- propellant 2004 and propellant 2004L. After prolonged exposure to high temperature cycles and humidity, inflators using propellant 2004 can degrade, causing the propellant to burn too quickly when ignited. The rapid burning can cause the inflator to rupture during deployment, potentially causing serious or even fatal injury to vehicle occupants. See 2016 Blomquist Report at www.nhtsa.gov/sites/nhtsa.gov/files/documents/expert_report-hrblomquist.pdf.Consequently, all frontal inflators using propellant 2004 that do not contain a "desiccant" (a substance that traps and holds moisture) in US vehicles are under recall. These "non-desiccated" inflators either have been or are required to be replaced.In some cases, the remedy part for these recalled inflators was, or will be, an inflator using either propellant 2004 or 2004L that does contain a desiccant. None of these "desiccated" remedy parts (which were installed in older model year vehicles) are currently under recall for a degradation concern. Certain subsets of desiccated PSAN inflators using propellant 2004 for use as original equipment, however, have been recalled for a degradation concern. All Takata inflators produced with propellant 2004L contain desiccant, and none of these desiccated inflators using propellant 2004L are under recall for a degradation concern. There have been no reported field ruptures in any non-recalled desiccated PSAN inflators.It is understood that desiccants fully saturate at some threshold, at which point any additional moisture will not be captured. This means the degradation process observed in non-desiccated inflators using propellant 2004 may also occur in non-recalled desiccated inflators using propellant 2004, assuming additional moisture enters the inflator and high temperature cycling occurs. Based on available information, desiccant saturation can occur within the first five years in the worst environments, and the time required for full saturation is affected by multiple factors. While no present safety risk has been identified, further work is needed to evaluate the future risk of non-recalled desiccated inflators using propellant 2004.Three entities -- Takata (now known as TK Global), the Independent Testing Coalition, and Exponent -- have been studying the long-term behavior of Takata desiccated PSAN inflators using propellant 2004L (as well as 2004) in the presence of moisture and temperature cycling. The research efforts, which include development of predictive modeling techniques and field sample analysis, are ongoing. To date, none of the researchers have identified field evidence showing that propellant 2004L is undergoing a degradation process that leads to aggressive deployment and potential rupture. However, the time in service of such inflators remains short compared to that of the inflators using propellant 2004. Further study is needed to assess the long-term safety of desiccated inflators using propellant 2004L.The Office of Defects Investigation is opening this investigation to examine whether a safety defect related to propellant degradation exists in non-recalled desiccated PSAN frontal inflators manufactured by Takata. This investigation will require extensive information on Takata production processes and surveys of inflators in the field. Lists of recall actions that may have used desiccated PSAN inflators as remedy parts, as well as the makes and models originally manufactured with them, is available with the downloadable version of this document (see nhtsa.gov/recalls?nhtsaId=EA21002 -- note this information is subject to change/revision as the investigation proceeds). This investigation does not supersede EA15-001, which remains open.

In a letter dated April 29, 2022, Mr. Sergio Betancourt (the petitioner) submitted a petition attributing engine failure of his 2015 Mercedes-Benz C300 to “wrong sized wrist-pins” and asserted that these were prevalent on all Mercedes-Benz models (including the Metris minivan, GLC300, and C300) equipped with a version of the M274 engine. The petition cited Mercedes Technical Service Bulletin (TSB) LI03.10-P-060916 (meant for the 2015 C300) and postulated that the “wrong-sized wrist pin” would allow the piston to “wiggle in the cylinder as it would move up and down”. In addition to the Mercedes-Benz TSB, the petitioner enclosed a service center repair estimate and images of other online submissions discussing the M274 engine. In the incident that prompted the petition, the petitioner reported that the vehicle lost power and shook in response to accelerator application during highway driving, followed by white smoke from the exhaust pipe. The petitioner stated that the subsequent service center visit led to a cracked piston diagnosis. The service record from this visit prescribed an engine teardown to localize the failure and characterize any resulting engine damage and listed a number of repair options that included replacement of one piston, four pistons, or the entire engine long block (depending on the level of damage suffered). TSB LI03.10-P-060916 (“TSB”) was first released on February 27, 2015 and pertained to Engine Code 274.920. It cited the following complaint condition: “Clattering/rattling or knocking noise from the crank assembly of the engine when cold at oil temperatures up to approximately 50°C mostly heard on engine deceleration” and listed the cause as under analysis. The TSB gave further instructions on the collection of information and discouraged the replacement of any components. On September 21, 2015, TSB Version 4 introduced engine build clean points (March 27, 2015 or April 20, 2015 depending on the engine plant); cause: unfavorable tolerance of the piston wrist pin resulting in enlarge end float of the connecting rod in the piston; and remedy: compare the complaint vehicle sound to an enclosed sound file under various operating conditions and then if verified, replace the pistons, connecting rods, and bearings, using updated pistons that include updated wrist pins. A review of the petitioner’s vehicle service history indicates that this labor operation was performed in March of 2016. In its November 22, 2022 response to ODI's September 28, 2022 Information Request (IR) letter, Mercedes stated that the limited number of potentially affected wrist pins could contribute to an unintended noise, but pose no motor vehicle safety risk. ODI's analysis of the field data furnished with the Mercedes IR response and within its own Vehicle Owners Questionnaire (VOQ) database support this assertion, finding no relationship between wrist-pin conditions cited in the TSB and engine failure or loss of motive power. Broader searches of both data sources for engine stalling related to engine durability identified no trends meriting further investigation. After conducting a technical review of the petitioner’s submissions, the vehicle history of the petitioner's vehicle, Mercedes TSB—LI03.10-P-060916, information provided by Mercedes-Benz in response to the Agency's Information Request, and data within its own files; NHTSA has concluded that there is insufficient evidence to pursue a formal investigation. Accordingly, the Agency has denied the petition. NHTSA will continue to review any new information or incidents as they are submitted to the Agency. A Federal Register Notice (FRN) further detailing NHTSA's reasons for denial of the petition will be published in the future. The petition and its attachments can be reviewed at NHTSA.gov under reference ODI number 11450360.

On January 8, 2021, after ongoing review with Mercedes Benz, the National Highway Traffic Safety Administration (NHTSA) Office of Defects Investigation (ODI) opened PE21-001 to assess allegations of front roof panel detachments while driving at highway speeds in certain 2015 Mercedes-Benz (Mercedes) C-Class vehicles.The subject front roof panel is a stationary panel composed of polycarbonate and is attached to the vehicle via adhesive at the time of manufacture. The panel is found on subject vehicles equipped with panoramic sunroofs. Over time, the subject panels may exhibit cosmetic degradation leading to replacement of the panel, a procedure which entails: removal of the old panel and adhesive, site preparation, and installation of a replacement panel with new adhesive.The consumer complaints that prompted the opening of PE21-001 all described detachments of front roof panels that had been replaced after the vehicle was put into service.Mercedes' internal investigation identified a broader scope of affected vehicles (2014-2020 CLA, GLA, C, S, GLC, and GLE class) and found the following potential service procedure- related causes of front roof panel detachments:- Improper surface pretreatments such as the use of the wrong primer or cleaner or scoring of the surface; or - Use of the incorrect adhesive.These conditions lead to a front roof panel bond that, even if sound at the time of repair, cannot maintain its strength over time and environmental exposure.Mercedes updated its service and parts ordering systems to reinforce the proper use of specified kits and procedures via webinars, shop foreman meetings, and explicit reference to the risks incurred by diverging from the repair procedures. Mercedes is also furnishing parts ordering assistance, and will hold dealerships accountable for improper repairs.ODI's analysis of the ten complaints it has received from the public (VOQ's) and MBUSA's complaint data submitted in response to the information request letter for PE21-001 identified a total of 57 non-duplicative reports alleging incidents in which the front roof panel detached from the vehicle while in motion. Included within the 57 reports are incidents where consumers state the panel detached ...and flew off into traffic.On March 19, 2021, Mercedes notified NHTSA that it would recall subject vehicles with front roof panels known to have been replaced after the original sale of the vehicle. In total, the recall (designated as Recall 21V197) covers 15,099 vehicles that were ever registered in the United States. Based on Recall 21V197 and the remedy implemented by Mercedes, further investigation does not appear to be warranted at this time.Accordingly, this investigation is closed.The ODI complaints cited above can be viewed at www.nhtsa.gov under the following ODI identification numbers: 11376425, 11352686, 11351629, 11349158, 11341541, 11337594, 11324100, 11311591, 11222127, 11404183

The contact owns a 2015 Mercedes-Benz C300. The contact stated that while driving at various speeds and depressing the brake pedal, the vehicle fishtailed on several occasions. The vehicle was taken to an independent mechanic, where it was raised on a lift, and the mechanic discovered that the rear subframe was severely corroded. The mechanic determined that the failure was associated with Manufacturer Communication Number: MC-10232321 (Structure); and referred the contact to a dealer for assistance. The vehicle was towed to the dealer, where the failure was confirmed, and it was discovered that the rear subframe had separated. The dealer informed the contact that the vehicle was unsafe to drive. The contact was provided an estimate for the repair and was informed that goodwill assistance would not be provided. The vehicle was not repaired due to the cost. The manufacturer was notified of the failure and informed the contact that the dealer was unreachable. The failure mileage was approximately 120,000.

NHTSA ID

11754977

Incident

Jul 15, 2026

Mileage

120,000 mi

The contact owns a 2015 Mercedes-Benz C300. The contact stated that while the vehicle was parked, the contact became aware that the panoramic roof failed to close as intended. The vehicle was taken to the dealer, where it was determined that the panoramic roof guide rails had failed. The contact was informed that the panoramic roof guide rails needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure, and a case was filed. The contact was informed that the mileage and age of the vehicle had exceeded the limitation. The failure mileage was approximately 110,000.

NHTSA ID

11753779

Incident

Apr 15, 2026

Mileage

110,000 mi

Rear subframe rust has deemed the car unsafe to drive. Hitting a pot hole at high speed or any sudden stop could cause the subframe to collapse causing loss of control of car. Car is available for inspection upon request. Car was taken in for regular oil change and multi-point inspection when rust was noticed by mechanic at the dealership. Car is located in East TN not the snow belt. There have been recalls on similar models for the year prior, but this vin is not part of the recall and has same issue, although the number 204 which is part of the recall is stamped on the part. (Pic attached below.)

NHTSA ID

11753660

Incident

Jul 2, 2026

The contact owns a 2015 Mercedes C300. The contact stated that the driver's side rear brakes and rotors were rusted. The contact stated that when the brakes were applied, they were slow to respond. The TPMS warning light was illuminated. The vehicle was taken to a braking center, which declined the warranty for the aftermarket parts. The local dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was not notified. The approximate failure mileage was 176,000.

NHTSA ID

11740646

Incident

Apr 1, 2026

Mileage

176,000 mi

I was driving my car was sputtering or trying to shut off while I press the gas and I let go of the gas and it catches and stayed on. I took it to the dealership and they said they found nothing wrong. May 3rd around 12pm im driving on the freeway and as im getting on the express lane going 60 it dies and I couldn't move the steering wheel and I slammed into a guardrail. After doing research my car (vin [XXX] ) had multiple recals from the fuel pump and steering wheel and the dealership never fixed or checked any recalls before selling it to me. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11736219

Incident

May 3, 2026

The contact owns a 2015 Mercedes-Benz C300. The contact stated that while driving at an undisclosed speed, there was an abnormal sound coming from the vehicle. The vehicle was driven to the shoulder of the road. The contact inspected the exterior of the vehicle and became aware that the moon roof panel had detached, and the moon roof panel flew off the vehicle. The dealer was made aware of the failure. The contact stated that the vehicle was previously repaired under NHTSA Campaign Number: 21V197000 (Structure) in 2021. The contact was informed that the repair was not covered under warranty. The vehicle was not diagnosed or repaired by an independent mechanic or the dealer. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was approximately 62,612.

NHTSA ID

11733048

Incident

Apr 17, 2026

Mileage

62,612 mi

The contact owns a 2015 Mercedes-Benz C300. While driving approximately 15 MPH, the brake pedal was depressed, and the body of the vehicle shifted to one side. The vehicle was drivable after the failure. There was no warning light illuminated. The vehicle was driven to the residence and parked. The contact stated that due to the failure, the vehicle was unsafe to drive. An independent mechanic was contacted, and it was determined that the rear subframe was corroded. The vehicle was not repaired. The manufacturer was notified of the failure, and it was confirmed that the VIN was not under recall. The failure mileage was not available.

NHTSA ID

11722220

Incident

Feb 16, 2026

Failed/Malfunctioned Component: Rear subframe (structural/chassis component) exhibited advanced corrosion (perforation/rust-through), compromising structural integrity and alignment/handling. Availability for Inspection: Yes. The vehicle and the subframe are available for inspection upon request. I can provide photos, videos, and repair estimates if needed. The corroded subframe is fracture and detach suspension mounting points, which may lead to: Sudden loss of vehicle stability or control (especially during braking, cornering, or over bumps). Unpredictable alignment changes causing pulling, vibration, or abnormal tire wear that can escalate into a loss-of-control event. Increased stopping distance and potential for wheel misalignment or collapse, raising the risk of a crash involving occupants and other road users. I limited driving/use due to the risk; issue is a structural safety concern rather than cosmetic. Confirmation: Yes on multiple visits since Oct 2023 -Yes—diagnosed and documented by Mercedes-Benz of Silver Spring on Oct 2 2023, Nov 2023 and Dec 2025. Technician confirmed severe corrosion/rust perforation on the rear subframe requiring replacement. No No

NHTSA ID

11712059

Incident

Aug 22, 2025

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 The customer requests deactivation of the N112/9 HERMES communication module Note: Deactivation of the HERMES control unit (N112/9) is not supported for gray-market vehicles. Cause Before deactivating the HERMES control unit (N112/9), it must be clarified by the legal department of the respective MPC whether and under what conditions deactivation may be carried out. If deactivation is not permissible under applicable law, the HERMES control unit (N112/9) must not be deactivated. Remedy Please inform the customer that, following deactivation, the vehicle will no longer be able to place an automatic emergency call, nor will the customer be able to place a manual emergency call. After deactivation, the Mercedes-Benz Digital Extras will also no longer be available. Please have the attached sample form checked by your market's legal department, adapted to local requirements if necessary, and approved. Furthermore, after informing the customer about the effects of deactivation, please have the workshop complete and sign the approved form together with the customer, and send it to the MPC via a TIPS case for audit-compliant documentation. Furthermore, the workshop must affix a sticker to the emergency call button cover on the overhead control panel and to the emergency call button itself. After affixing, pictures of the overhead control panel need to be attached to the TIPS case for audit-proof documentation. After deactivation, the HERMES control unit (N112/9) is in the "Out of Service" operating status, and the display "SOS NOT READY" appears in the Audio/COMAND system. This display message tells the customer that the emergency call function is not available. In detail, the following steps must be carried out 1. The workshop must inform the customer about the effects of deactivation (see above) 2. Legal review by the MPC Legal department to determine whether deactivation is permissible for the vehicle and provision of a market-specific customer form based on the examples (see "Example - Deactivation communication module HERMES customer declaration English V3.0.pdf") 3. Completion of the market-specific customer form by the workshop and obtaining the customer’s signature 4. Creation of a XSS ticket by the workshop for the MPC with the signed customer form attached 5. Written confirmation of legally reviewed and approved deactivation by the MPC in the TIPS case (see attachment How+to+request+adding+Code+09o+via+XSS+v2.pdf, point 1) 6. Creation of an XSS ticket for documentation of the SA code "09o" (zero nine oh) in the Vehicle Documentation System (see attachment How+to+request+adding+Code+09o+via+XSS+v2.pdf, steps 2–7) 7. Ordering of stickers (part number A9078172900), quantity: 2 8. Affixing of the sticker (part number A9078172900) to the cover of the emergency call button on the overhead control panel (see attachment HERMES-Deactivation_+pictures+of+sticker.png) 9. Affixing of the sticker (part number A9078172900) to the emergency call button on the overhead control panel (see attachment HERMES-Deactivation_+pictures+of+sticker.png) 10. Taking photos of the applied stickers and attaching them to the TIPS case 11. After the XSS ticket has been successfully processed, the communication module must be deactivated using XENTRY: • Connect XENTRY Diagnosis • Access the HERMES control unit (N112/9) • "Adaptation" tab, menu item "Teach-in processes" -> "Deactivation" • Follow the instructions

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"

Complaint There are several types of complaint about noises or poor windshield wiper wiping performance: A: Wiper blades squeaking, chattering, shuddering B: The windshield is not wiped completely (streaking) C: During the downward movement water is pulled back onto the windshield from the A-pillar (Figure 1) D: After windshield cleaning, water keeps spraying onto the windshield for several wipe cycles (Figure 2) A1: The windshield and wiper blades are contaminated with residues from car washing facilities, identifiable by the water beading. The resulting differences in the friction values between the wiper blades and the windshield can excite the wiper blades to vibrate. Note: It is mostly wax residue from the washer system, but also water-repellent nano-particle coating for paint and/or silicone-based washer fluid, that could cause this problem. A partially dry windshield also has different friction values, which can likewise result in squeaking of the wiper blades A2: The wiper blades are worn by mechanical damage (wiper lip damaged by ice or insect debris, or deformed by long periods of disuse). A3: Incorrect angle of incidence of the wiper arms to the windshield. Because of this, the rubber lip of the wiper blade may not flip over at the reversal point. Cause B: B1: Wax/ dirt residues on the windshield B2: Wiper blades deformed or worn B3: Downforce of wiper arm not OK (Figure 3) Cause C: Water is pulled back onto the windshield by the differential pressure created as the wiper arm moves downwards. Cause D: Washer water collects in the fastening of the wiper blade and is blown onto the windshield by the airstream over several wipe cycles. Note and supporting information: Wiper blades are wear parts which, even when "not used" for long periods (kept in park position), may become permanently deformed and damaged. Further stresses on the rubber wiper blade arise due to various environmental influences which progressively change the effectiveness of the rubber wiper blade and accelerate the aging process. Due to the natural aging process and wear, the wiper blades should be replaced twice a year, preferably in Spring and Fall (see operator's manual). Remedy Remedy A: A1: Cleaning entire windshield with A 000 986 40 71. A2: Checking water's flow behavior after windshield has been cleaned (see Video 1). If, after cleaning, there are still areas with water beading, then the cleaning process must be carried out again until a rejection reaction is no longer present. • Note: On the vehicle in the video (Video 1), water still beads on the bottom left of the windshield. The windshield is still not properly clean, even though it appears to be clean. The windshield is only properly clean when there are no more areas on the windshield where water beads. A3: Replace wiper blades with genuine wiper blades. Important: Only exchange wiper blades if windshield no longer has water-repellent areas Note: Replacement of wiper blades is not covered under warranty and can be replaced at the expense of the customer. Remedy B: B1: Clean windshield with intensive cleaner A 000 986 40 71. Important: Do not clean the wiper blades otherwise the graphite coating will be damaged. B2: Replace wiper blades with genuine wiper blades • Note: Replacement of wiper blades is not covered under warranty and can be replaced at the expense of the customer. B3: Check the wiper arm for excessive resistance in the bearing. Restore mobility or replace wiper arm if necessary. Remedy C: Problem inherent in design for which there is no technical remedy. Exception: X204 up to 02/2014. In these vehicles, it is possible to install the design configuration of vehicles as of 02/2014. This includes wiper arms (styled arms) with improved behavior in this respect. It is also necessary to replace the wiper blades because the styled arms feature a Top Lock connection (previously Side Lock).