Total Complaints
14 filings
MERCEDES-BENZ C 300 · model year
14 NHTSA complaints, and 5 active recalls for this specific cohort.
NHTSA overall rating
Not crash-tested
New Car Assessment Program
The 2021MERCEDES-BENZC 300 carries 14 consumer safety complaints in NHTSA's Office of Defects Investigation database for this specific model-year cohort. Within that volume, owners reported 0 crashes, 0 fires, 0 injuries, and 0 fatalities. No NCAP 5-star crash-test rating is available for this model year in the federal database.
Component-level analysis is where model-year complaints become actionable: the top complaint category for the 2021 C 300 is engine with 7 filings, followed by fuel/propulsion system (2) and air bags (1). Concentration in one or two component groups is the classic signature of a systemic defect; a flat distribution usually reflects normal aging, warranty complaints, or isolated build-plant variability. This model year has 5 active recall campaigns, which means the manufacturer is obligated to remedy the covered defect at no charge for the life of the vehicle — the full NHTSA campaign numbers are listed below.
NHTSA currently has 15 investigation files overlapping the 2021 C 300. Owners comparing this cohort against neighboring years should pair the counters above with the complaint-by-year trend on the parent model page — a spike in a single year often tracks to a platform refresh, a new transmission supplier, or an updated ECU calibration. Use the related-complaint feed below to read raw owner narratives before deciding whether any pattern here affects your specific use case.
Total Complaints
14 filings
Crashes Reported
0 reports
Source
NHTSA ODI
Federal complaints database
At or below the fleet median complaint volume.
| Component | Count |
|---|---|
| ENGINE | 7 |
| FUEL/PROPULSION SYSTEM | 2 |
| AIR BAGS | 1 |
| ELECTRICAL SYSTEM | 1 |
| BACK OVER PREVENTION: SENSING SYSTEM: CAMERA | 1 |
| POWER TRAIN | 1 |
| VISIBILITY:SUN/MOON ROOF ASSEMBLY | 1 |
SEAT BELTS:FRONT:RETRACTOR
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 2
FUEL SYSTEM, GASOLINE:DELIVERY:FUEL PUMP
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.
ELECTRICAL SYSTEM:SOFTWARE
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 de
BACK OVER PREVENTION:DISPLAY FUNCTION
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 disp
ELECTRICAL SYSTEM:SOFTWARE
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 mod
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 operation of the vehicle. The defect creates a safety concern because it can distract the driver, allow water intrusion that may affect electrical components, and/or cause sudden glass or mechanical failure while driving. The vehicle has been taken to a Mercedes-Benz dealership for diagnosis and the issue was not resolved due to denied coverage. I was informed that the repair would be costly despite the issue appearing to be a known defect in Mercedes-Benz panoramic sunroof systems. I believe this defect may affect other Mercedes-Benz vehicles with panoramic sunroofs and should be investigated for a potential safety defect or recall.
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 vehicle was taken to an independent mechanic, where it was diagnosed and determined that there was a misfire in cylinder #2. The contact was informed that the cylinder head needed to be replaced. The vehicle was not repaired. The vehicle was then taken to the dealer, where the same diagnostic information was provided, and the contact was informed that the cylinder head needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 86,078.
Mileage: 86,078
My car had a coolant leak last year a hose broke and I have a 2021. My sonâs 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.
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 2021â2023 M254 engines with multiple documented failures under 50k miles. Sudden loss of compression and misfires create a safety risk of engine failure or fire while driving. TSB NUMBER LI07.16-P-074000 (February 2023, updated multiple times). This is a known production/early break-in issue with the M254 engine, not the result of owner misuse or delayed maintenance.
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.
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 may cover it since it is a "known problem" and shouldn't happen with that mileage. I was charged $7,860 by my local Mercedes dealer, and despite multiple contacts with MercedezUSA, they refuse to acknowledge this is a problem or cover the cost, although in on-line the forums some people were arbitrarily reimbursed. There should be a recall to check for this obvious defect and should be covered. This defect can cause sudden engine failure and is a significant hazard to the driving public.
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 may cover it since it is a "known problem" and shouldn't happen with that mileage. I was charged $7,860 by my local Mercedes dealer, and despite multiple contacts with MercedezUSA, they refuse to acknowledge this is a problem or cover the cost, although in on-line the forums some people were arbitrarily reimbursed. There should be a recall to check for this obvious defect and should be covered. This defect can cause sudden engine failure and is a significant hazard to the driving public.
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.
Rearview camera not displaying any image when transmission is put in reverse.
the check Engine light fault code P012D12 The pressure sensor upstream of the turbocharger had a short circuit to positive. Found Kink wire on upstream pressure sensor. A short circuit to positive. Electrical Wire replaced.
First day leasing the vehicle within 6 hours lights malfunction and malfunction warning on dash to seek workshop, vehicle was taken for inspection to original dealer (Mercedes Benz of Bakersfield). During inspection I added additional concerning complaints about passenger door not closing correctly/wind noise seeping through when closed, and hood not closing promptly. One month into leasing vehicle passenger window malfunction, took for inspection and repair to original dealer (MBofBakersfield). Concerned with caution for me, my family, and friends when in that vehicle for giving faulty signs so early. One year into leasing vehicle check coolant warning on dash, took for inspection to original dealer. I am now more concerned as it went form electrical to coolant components losing coolant with no reasoning from original dealer service other then a top off. Vehicle drive is rough. 1 year and 6 months into leasing vehicle, again check coolant warning on dash. Took in for inspection, gave
First day leasing the vehicle within 6 hours lights malfunction and malfunction warning on dash to seek workshop, vehicle was taken for inspection to original dealer (Mercedes Benz of Bakersfield). During inspection I added additional concerning complaints about passenger door not closing correctly/wind noise seeping through when closed, and hood not closing promptly. One month into leasing vehicle passenger window malfunction, took for inspection and repair to original dealer (MBofBakersfield). Concerned with caution for me, my family, and friends when in that vehicle for giving faulty signs so early. One year into leasing vehicle check coolant warning on dash, took for inspection to original dealer. I am now more concerned as it went form electrical to coolant components losing coolant with no reasoning from original dealer service other then a top off. Vehicle drive is rough. 1 year and 6 months into leasing vehicle, again check coolant warning on dash. Took in for inspection, gave
Piston Connecting Rod broke and left the engine making holes in both sides of the block; Mercedes Benz rejected any responsibility because the car has a branded title. Currently a new engine (brand new) is being installed, my concern is that what will happen if the new engine has the same defective part and blew up again.
The contact owns a 2021 Mercedes-Benz C300. The contact stated while driving at an unknown speed, there was a burning odor inside the vehicle. The contact stated the passenger side air bags was enabled warning light was illuminated. The contact also stated the vehicle made an abnormal noise. The contact took the vehicle to the local dealer but was unable to duplicate the failure. The manufacturer had not been informed of the failure. The failure mileage was unknown.
Data as of 2025. Sources: NHTSA Office of Defects Investigation (ODI) complaints database, NHTSA recall campaign API, NHTSA NCAP crash-test ratings, and NHTSA FARS for fatality cross-reference.
Read our methodology — how this data is sourced, computed, and verified.