2021 Mercedes-Benz C 300 problems, complaints & recalls
Most-reported problem areas: Engine (7) · Fuel/Propulsion System (2) · Visibility:sun/Moon Roof Assembly (1)
🧭 Reliability snapshot
Compared against other Mercedes-Benz C 300 model years — complaint volume vs the model's median year, recalls and severity. How we score →
Safety recalls (7)
Fuel System, Gasoline:delivery:fuel Pump 2023-06-26 · campaign 23V445000 · 143,551 vehicles
Defect: Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021-2023 C-Class, E-Class, S-Class, CLS, SL, GT, GLC, GLE, GLS, and G-Class vehicles. Please refer to MBUSA's recall report for specific vehicle details. The fuel pump may shutdown, which can result in a loss of drive power.
Risk: A loss of drive power can increase the risk of a crash.
Fix: Dealers will replace the fuel pump, free of charge. Owner notification letters were mailed on June 14, 2024. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2023070012.
Communication: Auto Crash Notification 2022-05-20 · campaign 22V365000 · 242,722 vehicles
Defect: Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2017-2022 CLA-Class, GLA-Class, GLE-Class, GLS-Class, SLC-Class, A-Class, AMG GT-Class, C-Class, E-Class, S-Class, SL-Class, GLC-Class, CLS-Class, GLB-Class, and G-Class vehicles. Please refer to MBUSA's recall report for specific vehicle model details. An error in the communication module's SIM card software can cause a mobile network connection failure, disabling the emergency call (eCall) system.
Risk: A disabled eCall system would prevent a vehicle occupant from contacting the emergency services call center in an emergency, potentially delaying emergency responders and increasing the risk of injury.
Fix: The communication module software will be updated through an Over-the-Air (OTA) update or by a dealer, free of charge. Owner notification letters were mailed July 8, 2022. Owner notification letters will be mailed in phases, on July 8, 2022, May 17, 2024, July 29, 2024, and September 27, 2024. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's numbers are for this recall is 2022060005 and 2023110006.
Back Over Prevention:display Function 2022-04-08 · campaign 22V232000 · 126,443 vehicles
Defect: Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2018-2021 CLA-Class, GLE/GLS-Class, A-Class, C-Class, E-Class, E-Class Coupe/Convertible, GLA/GLB-Class, GLC-Class, and CLS-Class vehicles. Please refer to MBUSA's recall report for specific vehicle model details. The rearview camera may not display the rearview image due to a software error. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 111, "Rear Visibility."
Risk: An inoperable rearview camera display reduces the driver's rear view, increasing the risk of a crash.
Fix: Dealers will update the rearview camera software, free of charge. Owner notification letters were mailed July 15, 2022. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2022060007.
Seats:mid/Rear Assembly:head Restraint 2021-05-28 · campaign 21V406000 · 218 vehicles
Defect: Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021 C300 Cabriolet, C43 AMG Cabriolet, C63 AMG Cabriolet, C63 AMG S Cabriolet, E450 Cabriolet, and E53 AMG Cabriolet vehicles. The rear headrests may be incorrectly mounted to the seatbacks.
Risk: Incorrectly mounted headrests could move or detach from the seat during a crash, increasing the risk of injury.
Fix: Dealers will inspect the rear seatback guide bushings and replace them if necessary, free of charge. Owner notification letters were mailed July 16, 2021. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2021060010.
Seat Belts:pretensioner 2021-04-01 · campaign 21V230000 · 8,634 vehicles
Defect: Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021 C-Class, E-Class, E-Class Coupe and Convertible, GLC, CLS, AMG GT 4-door Coupe and G-Class vehicles. Please refer to MBUSA's recall report for specific vehicle model details. A faulty electrical contact within the seat position switch may prevent the driver and passenger air bags and seat belt force limiters from properly activating during a crash.
Risk: Air bags and seat belts that do not perform properly in a crash can increase the risk of injury.
Fix: MBUSA will notify owners, and dealers will replace the seat position switches, free of charge. Owner letters were mailed May 21, 2021. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2021040016.
Communication: Auto Crash Notification 2021-02-05 · campaign 21V058000 · 1,292,258 vehicles
Defect: Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2016 - 2021 CLA-Class, GLA-Class, GLE-Class, GLS-Class, SLC-Class, A-Class, GT-Class, C-Class, E-Class, S-Class, CLS-Class, SL-Class, B-Class, GLB-Class, GLC-Class, and G-Class vehicles. Please refer to the Part 573 report for specific vehicle model details. The software design of the communication module may fail to communicate the correct vehicle location for the emergency call system (eCall) in the event of a crash.
Risk: Failure of the eCall system may result in emergency responders being dispatched to the wrong location, increasing the risk of injury following a crash.
Fix: MBUSA will notify owners, and the communication module software will be updated by a dealer, or through an over-the-air (OTA) update, free of charge. The recall began March 12, 2021. Owners may contact MBUSA customer service at 1-877-762-8267. MBUSA's number for this recall is 2021020025.
Seat Belts:front:retractor 2021-01-29 · campaign 21V032000 · 24,550 vehicles
Defect: Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2017-2021 C300, 2017-2020 AMG C43, and AMG C63 vehicles. The front seat belts might not fully retract to their stowed position. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 208, "Occupant Crash Protection."
Risk: If the seat belt does not fully retract, the occupant may find the operation of the seat belt inconvenient and not wear it, increasing the risk of injury in the event of a crash.
Fix: MBUSA will notify owners, and dealers will check the retraction function of the front seat belts and adjust the damping foam within the B-pillars, as necessary, free of charge. The recall began February 26, 2021. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2021020010.
Service bulletins (178)
Technical service bulletins are repair instructions manufacturers send dealers for known issues. Unlike recalls, the fix is not automatically free — but naming the bulletin at the service desk can save diagnosis time and support goodwill repairs.
Steering 2026-09-26 · LI46.10-P-080896 · Service Bulletin/Repair Instructions
complaint slight creaking noises when steering. cause noises may come from one or more sleeves of the horn contact plate. remedy remove the horn contact plate and check the sleeves for noise; see attached video. if necessary, apply lubricant to the sleeves.
Power Train 2026-09-26 · LI27.00-P-073124 · Service Bulletin/Repair Instructions
complaint customer complaints relating to automatic transmission 725.0 (nag3 classic /9g‑tronic automatic transmission) and 725.1 (nag3 facelift/9g‑tronic automatic transmission facelift) for faster, more effective and more targeted diagnosis, intelligent predictive repair (ipr) has been developed a
Service Brakes 2026-09-22 · LI42.10-P-078779 · Service Bulletin/Repair Instructions
complaint repeat workshop visit for vehicle vibration while braking from 60mph. note: although the symptom is similar to a tire or wheel vibration, it is usually readily noticeable that it is distinctly different if it happens at all times or only while braking. cause although the cause of the vibra
Structure:body 2026-09-14 · LI82.62-P-078631 · Service Bulletin/Repair Instructions
complaint clanking noise from the area of the speakers in the doors. cause under analysis. remedy to narrow down the cause, first of all remove the door trim. • if the noise continues to occur even with the door trim removed, then continue the diagnosis working towards the speaker and if necessary,
Power Train 2026-09-14 · LI27.10-P-075869 · Service Bulletin/Repair Instructions
complaint only vehicles with a variable transfer case are affected. this can be identified through control unit n45 or n15/7 in the quick test. when accelerating with light load, vibrations or jolting sensation may come from the drivetrain. it may be mistaken for a harsh shift. cause modified oil qu
Power Train 2026-09-04 · LI27.00-P-073124 · Service Bulletin/Repair Instructions
complaint customer complaints relating to automatic transmission 725.0 (nag3 classic / 9g‑tronic automatic transmission) and 725.1 (nag3 facelift/9g‑tronic automatic transmission facelift) for faster, more effective and more targeted diagnosis, intelligent predictive repair (ipr) has been developed
Showing the 6 most recent of 178 bulletins. Search all of them free at nhtsa.gov.
What owners report
2026-08-07 · Engine · 88,000 mi“the contact owns a 2021 mercedes-benz c 300. the contact stated that while depressing the accelerator pedal, there was a loud knocking sound coming from the engine compartment while accelerating. there were no warning lights illuminated. the vehicle was taken to the dealer to be diagnosed, and it was determined that the spawn rod was fractured, cau…”
2026-05-19 · Fuel System, Gasoline · 60,000 mi“the contact owns a 2021 mercedes benz c. the contact stated that while driving on the highway, the vehicle began to lose power, riding rough. the check engine light illuminated. the vehicle was towed to the dealer where it was diagnosed with a fuel injection failure. the vehicle read diagnostic code p1cef85. the manufacturer was made aware of …”
2026-01-20 · Visibility:sun/Moon Roof Assembly“i am reporting a safety defect involving the panoramic sunroof on my 2021mercedes-benz coop vehicle. the panoramic sunroof has malfunctioned due to an apparent design or manufacturing defect. the sunroof fails to open / close and makes grinding or popping noises which malfunctioned unexpectedly. this issue occurred without misuse and during normal…”
2025-12-22 · Engine · 86,078 mi“the contact owns a 2021 mercedes-benz c300. the contact stated that while driving at an undisclosed speed, the vehicle stalled and failed to exceed 30 mph, with the check engine warning light illuminated. the vehicle did not require a restart. the contact also stated that while stopped at a traffic light, the vehicle was shaking abnormally. the veh…”
2025-11-25 · Fuel/Propulsion System“my car had a coolant leak last year a hose broke and i have a 2021. my son’s mercedes sis the same thing on 11/23/2025. i have researched ma y others with this same issue. there should be a recall on that hose or whatever the problem is. …”
2025-11-25 · Engine“2021 mercedes-benz c300 with m254 2.0l turbo engine experienced sudden cylinder head failure at 44,000 miles due to manufacturing porosity in the cylinder head and camshaft bore scoring. dealer confirmed defect. this is a known, recurring issue on 2021–2023 m254 engines with multiple documented failures under 50k miles. sudden loss of compression a…”
2025-10-06 · Fuel/Propulsion System“while driving car on sunday 10/5, it suddenly failed to respond to gas pedal pressure. the car stopped accelerating and rather slowed to 15 mph, almost causing a car from behind to hit me in the rear side. …”
2025-08-06 · Power Train“my c300 only had about 42,000 miles and was less than 5 years old. just after the factory warranty expired, the engine was running rough and hot, and "check engine" light illuminated. my local garage quickly diagnosed the problem as a failed cylinder head, stated that it is common with mercedes 4-cylinder engines from about 2017, and said mercedes …”
2025-02-17 · Engine“cylinder head needed to be replaced on the m264 engine at 35,000 miles. the replacement part is also known to be defective for the same reasons. this is a common defect known to the manufacturer and they have not issued a recall. my concern is that of a roadside breakdown that would endanger my wife and myself. thank you for your consideration.…”
2024-11-04 · Back Over Prevention: Sensing System: Camera“rearview camera not displaying any image when transmission is put in reverse.…”
Excerpts of consumer complaints filed with NHTSA, lightly truncated. They are owner statements, not verified findings.