Problems › Mercedes-Benz › 2021 C-Class
2021 Mercedes-Benz C-Class Problems & Owner Complaints
Age-normalised, this year draws ~2.3 complaints per year on the road — ranking 15 of 15 Mercedes-Benz C-Class years we track (1 = most complaints per year).
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What owners report
Engine is the most-reported problem area on the 2021 Mercedes-Benz C-Class, cited in 7 of 14 filed complaints (50%).
Air Bags is next (2 complaints, 14%), followed by Fuel/Propulsion System (2), Power Train (2), Back Over Prevention (1).
No complaint for this vehicle reports a crash, fire, injury or death.
Complaints by vehicle system
Owner complaints filed with the U.S. NHTSA for the 2021 Mercedes-Benz C-Class, grouped by the vehicle system each cites. A single complaint can name more than one system, so the group totals can add up to more than 14.
Engine 7
“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…”
NHTSA complaint #11706514, 2025
“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 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 del…”
NHTSA complaint #11701560, 2025
“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, alth…”
NHTSA complaint #11678865, 2025
Air Bags 2
“Driving and something came from underneath the vehicle and cause me to swerve in all the airbags deployed”
NHTSA complaint #11704073, 2025
“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.”
NHTSA complaint #11453645, 2021
Fuel/Propulsion System 2
“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.”
NHTSA complaint #11701496, 2025
“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.”
NHTSA complaint #11691568, 2025
Power Train 2
“Driving and something came from underneath the vehicle and cause me to swerve in all the airbags deployed”
NHTSA complaint #11704073, 2025
“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, alth…”
NHTSA complaint #11678865, 2025
Back Over Prevention 1
“Rearview camera not displaying any image when transmission is put in reverse.”
NHTSA complaint #11623522, 2024
Electrical System 1
“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…”
NHTSA complaint #11568290, 2024
Fuel System 1
“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 the issue. The approximate failure mileage was 60,000.”
NHTSA complaint #11738727, 2026
Suspension 1
“Driving and something came from underneath the vehicle and cause me to swerve in all the airbags deployed”
NHTSA complaint #11704073, 2025
Visibility 1
“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 take…”
NHTSA complaint #11712287, 2025
How we read this (methodology)
How to read this: raw complaint totals are not a clean reliability score — a model year with more cars sold, or simply more years on the road, accumulates more complaints regardless of how good it is. So this page leans on two signals that are not distorted by sales volume: the share of complaints falling on each vehicle system (the breakdown above) and NHTSA's own crash / fire / injury / death flags. When we compare model years of the same model, we normalise by years on the road (complaints ÷ vehicle age) rather than comparing raw totals. Age-normalised, the 2021 Mercedes-Benz C-Class draws about 2.3 complaints per year on the road, ranking 15 of 15 among the Mercedes-Benz C-Class model years we have ingested (1 = most complaints per year on road).
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Data source: U.S. NHTSA (nhtsa.gov). SaveVIN surfaces public recall data and is not affiliated with or endorsed by NHTSA.