2020 Mercedes-Benz C-Class Problems & Owner Complaints

Engine 9

“The contact owns a 2020 Mercedes-Benz C300. The contact stated that while at a stop, the vehicle failed to accelerate as intended. There was no warning light illuminated. The dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 100,000.”
NHTSA complaint #11731613, 2026

“I am reporting a catastrophic repeat engine failure on my 2020 Mercedes-Benz C300. On October 9, 2025, with 26,589 miles, the vehicle suffered a Cylinder 2 failure (exhaust valves), causing a dangerous loss of power in traffic. I paid $4,100.43 for a $10,000 plus cylinder head replacement at an authorized dealer (Mercedes-Benz of Atlanta South) on November 13, 2025. Following the repair, the vehicle continued to exhibit multiple 'Check Engine Oil Level' warnings. On February 4, 2026—less than 90 days after the major repair—the engine suffered a total catastrophic failure. The dealer now states…”
NHTSA complaint #11718583, 2025

“I purchased this 2020 Mercedes-Benz C300 only two months ago and have driven it less than 3,000 miles. The Carfax report shows consistent maintenance and regular service history by prior owners. While driving, the check engine light came on and the vehicle began shaking and running roughly. Diagnostics by Peachtree Imports (10/03/2025) and later by Mercedes-Benz of Atlanta South confirmed Cylinder #2 failure on the M264 2.0L engine at only 26,589 miles. The dealer’s report states: “Cylinder #2 mixture formation out of spec. Fault occurred due to worn exhaust valve seat. Cylinder head replacem…”
NHTSA complaint #11695702, 2025

Power Train 7

“I purchased this 2020 Mercedes-Benz C300 only two months ago and have driven it less than 3,000 miles. The Carfax report shows consistent maintenance and regular service history by prior owners. While driving, the check engine light came on and the vehicle began shaking and running roughly. Diagnostics by Peachtree Imports (10/03/2025) and later by Mercedes-Benz of Atlanta South confirmed Cylinder #2 failure on the M264 2.0L engine at only 26,589 miles. The dealer’s report states: “Cylinder #2 mixture formation out of spec. Fault occurred due to worn exhaust valve seat. Cylinder head replacem…”
NHTSA complaint #11695702, 2025

“Vehicle has ongoing and recurring electrical and engine-related defects that affect safe operation. The primary systems involved are the electrical system, engine ignition system, and powertrain. The vehicle is available for inspection upon request. Prior service records show issues beginning in 2020 involving repeated electronic system failures requiring multiple repairs and component replacements. Since purchasing the vehicle in April 2023, the vehicle has developed more serious failures, including: – September 2024: Check engine light with loss of power and inability to exceed safe drivin…”
NHTSA complaint #11733212, 2024

“My wife was driving our 2020 Mercedes Benz C300 coupe near our house and the engine light came on. Then the car could not be driven over the speed of 30 miles per hour. Then it stopped and had to be towed. Fortunately, she was able to avoid being hit by other vehicles.The car only has 25219 miles. It was towed to a mechanic who performed a diagnostic test which provided a series of codes regarding the malfunction. Three codes were related to the CAMTRONIC camshaft system and its Solenoid ( Codes: P003C-53; P34AE-00; P34AD-09). Camshaft position actuators Failure codes: P34AD; P34AE. The way…”
NHTSA complaint #11589214, 2024

Unknown Or Other 7 1 crash 2 injury

“While driving on the turnpike without warning my steering locked and I lost control of my car.”
NHTSA complaint #11423100, 2021 · crash · 2 injury(ies)

“THE COMPONENT THAT IS MALFUCTIONING IS THE COVERTABLE TOP OF MY 2020 C300 CABRIOLET MERCESDES BENZ. THE STRINGS/CORDS THAT HOLD THE LINER OF THE COVERTABLE TOP TO THE ROOF ARE BREAKING AND IT MAKES THE COVERTIBLE TOP INOPERABLE. THERE WAS NO WARNING LAMP OR NOTICE OF THIS DEFECT. THERE IS ONLY 11595 MILES ON MY 4 YEAR OLD CAR THAT IS GARAGED. THIS OCCURRED 1 YEAR AFTER MY WARRANTY EXPIRED. THIS WOULD CAUSE THE TOP TO BE STUCK IN THE MIDDLING OF OPENING AND IT COULD NOT BE MOVED MECHANICALLY TO GET IT FULLY OPENED OR CLOSED TO THE WEATHER AND IS UNDRIVABLE.THE COST TO REPAIR IT IS ESTIMATED B…”
NHTSA complaint #11635599, 2024

“I was driving on the highway, with no other cars near me and my panoramic sunroof exploded. It made a very loud gunshot like sound and I felt shards of glass fall on my head while driving. I had 2 other passengers In the car. One in the passenger set and one in the rear passenger side seat. They both had glass hit them in the face on head and go inside their clothes. I was extremely startled thinking that someone had shot at us or something and had to quickly take a highway exit to pull over and see what happened. Apparently this is a common thing with Mercedes as there is a class action lawsu…”
NHTSA complaint #11622207, 2024

Electrical System 5 1 crash 1 injury

“I own a 2020 Mercedes-Benz C300 equipped with a power trunk. On July 22, 2026, I took my vehicle to Annapolis Mercedes-Benz because the power trunk was repeatedly closing on its own while people were standing in the trunk opening. I specifically reported that the trunk was unexpectedly closing while I, my child, or another individual was loading or unloading the vehicle and expressed concern that someone could be injured. The dealership kept the vehicle for several hours but advised me that no malfunction could be found. I was told the trunk had been reset and that there were no problems with…”
NHTSA complaint #11754327, 2026 · 1 injury(ies)

“The contact owns a 2020 Mercedes-Benz C300. The contact stated that her son was driving at an undisclosed speed when another vehicle's muffler detached and crashed into the undercarriage of the contact's vehicle. The front driver and passenger side tires exploded and fractured the rims. The contact stated that the vehicle's alert system failed to warn her son of the incoming object which resulted in the collision. The contact's son did not receive medical attention. A police report was filed. The vehicle was towed to the dealer and repaired. The manufacturer was made aware of the failure but p…”
NHTSA complaint #11418528, 2020 · crash

“Car stops accelerating and shifts into neutral without warning I nearly got hit from behind. I have consulted several other Mercedes vehicle owners and all had the same issue. Two of the other owners stated that this happened on the interstate and was very lucky they were not involved in a collision. Both vehicles were GLC 300. Mercedes does not seem to have an answer to the issue and all previous owners traded vehicles for fear of dying.”
NHTSA complaint #11729030, 2026

Back Over Prevention 4 2 crash

“The contact owns a 2020 Mercedes-Benz C300. The contact was reversing out of her driveway at 3 MPH, the contact was using her rearview camera. The contact stated that the image froze and she crashed into a parked vehicle with the rear passenger side bumper of her vehicle. The contacts bumper was scratched and dented. The other vehicle had sustained a large dent in the driver’s side door. The contact stated no warning light was illuminated. The contact had taken the vehicle to a local repair and not a dealer or an independent mechanic. The vehicle had been repaired cosmetically. The manufacture…”
NHTSA complaint #11475739, 2022 · crash

“The contact owns a 2020 Mercedes-Benz C300. The contact stated that suddenly the vehicle's sensors were illuminating and activating a warning stated that the sensors were defective. Many of the vehicle's sensors began to deactivate and malfunction. While reversing out of a parking space the rear view camera and sensor system failed causing the contact to crash into another vehicle. Both vehicles were damaged. A police report was filed. There were no injuries reported. The vehicle was not towed. The contact took the vehicle to a repair facility and stated that there was damage to the internal s…”
NHTSA complaint #11469155, 2022 · crash

“The contact owns a 2020 Mercedes-Benz AMG C43. The contact received notification of NHTSA Campaign Number: 22V232000 (Back Over Prevention) however, the part to do the recall repair was not yet available. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The dealer was made aware of the issue. The manufacturer was made aware of the issue. The contact had not experienced a failure. Parts distribution disconnect.”
NHTSA complaint #11516496, 2023

Fuel/Propulsion System 4

“I purchased this 2020 Mercedes-Benz C300 only two months ago and have driven it less than 3,000 miles. The Carfax report shows consistent maintenance and regular service history by prior owners. While driving, the check engine light came on and the vehicle began shaking and running roughly. Diagnostics by Peachtree Imports (10/03/2025) and later by Mercedes-Benz of Atlanta South confirmed Cylinder #2 failure on the M264 2.0L engine at only 26,589 miles. The dealer’s report states: “Cylinder #2 mixture formation out of spec. Fault occurred due to worn exhaust valve seat. Cylinder head replacem…”
NHTSA complaint #11695702, 2025

“The component that failed was the fuel injector and spark plug. A few months prior to this incident, I was making a left hand turn, when the accelerator completely gave out. I was making the left on a blinking yellow arrow, luckily the on coming car was not coming at me fast or I would've been in an accident due to the accelerator failing. I had to pull over, turn the car off and then back on to reset it. I was told by the dealership service center that they could not find anything and that there have been no complaints or recalls. After about 8 months of owning the vehicle, it started to have…”
NHTSA complaint #11490902, 2022

“CEL with multiple cylinder misfires. Oil leak on top side of engine bank 2 in valley of injectors. Multiple codes for turbo charger faults and also clogged catalytic converters. Dealer confirmed and manufacturer denied federal emissions warranty on vehicle. Due to a modification that plays no role in the power train.”
NHTSA complaint #11497171, 2021

Structure 4

“Automatic trunk closing mechanism caused the trunk hood to close on my head as I was putting groceries in the trunk. This has occurred several times in the past but this time it hit my head with more force. I have not brought it to a dealer and it has not been inspected by the manufacturer, police or any other entity. There was no warning or alarm before it closed. This could cause serious head injury to an individual on blood thinners.”
NHTSA complaint #11747837, 2026

“The contact owns a 2020 Mercedes-Benz C300. The contact stated that a section of the roof near the top of the windshield, between the sunroof, had detached and flown off the vehicle while driving 30 MPH in bumper-to-bumper traffic. The driver was able to grab the portion of the rubber gasket and pulled it into the vehicle through the driver’s side front window. The roof was in three pieces. The contact turned on the hazard lights and was able to pull over safely to the side of the roadway. There were no warning lights illuminated. The contact was concerned about the failure potentially causing…”
NHTSA complaint #11678311, 2025

“On Tuesday, June 24th, 2025, the glass panel located between the windshield and sunroof on my 2020 Mercedes-Benz C43 AMG unexpectedly detached and flew off while driving. This posed a serious safety risk to me and others on the road. There were no prior warning lights, messages, or symptoms before the failure occurred. This appears to have resulted from heat stress weakening the bonding that secures the panel to the vehicle—an issue consistent with NHTSA Recall 23V854000. That recall covers my exact year, make, and model, yet my specific VIN has not been included for reasons unknown, despite…”
NHTSA complaint #11669230, 2025

Air Bags 3 1 injury

“On July 17, 2021 I was driving at the posted rate of speed down I-275 Southbound here in Michigan. All of the sudden and without warning, there was a loud explosion which happened, from as near as I can tell, in the driver's side windshield pillar, where there is an airbag. No warning lights came on, and the car did not change its driving characteristics. Only after I reached my destination and searched under the dash, and every where else (including the exterior), did I find that the plastic "cover" on the pillar is pushed away from the pillar and much more loose than the plastic cover on the…”
NHTSA complaint #11428078, 2021 · 1 injury(ies)

“I purchased this vehicle on December 26, 2025 from an authorized Mercedes-Benz dealership. Shortly after the purchase, I discovered an issue related to the airbag system, which indicates a potential safety defect. At the time of purchase and during the test drive, the vehicle was already turned on, and no warning or disclosure was provided regarding any airbag malfunction or warning message. The issue became apparent only after the purchase. I later brought the vehicle in for repairs. While some repairs were performed, the airbag issue was not fixed and remains in the same condition as befor…”
NHTSA complaint #11712823, 2025

“THERE IS A RECALL ON MY CAR. THE AIRBAGS HAVE NOT BEEN REPLACED YET. THE RECALL WAS ISSUED A LONG TIME AGO. *TR”
NHTSA complaint #11325066, 2020

Forward Collision Avoidance 3 1 crash 1 injury

“Automatic emergency braking system & forward collision warning. I experienced a medical emergency and blacked out, hitting 3 cars. The incident happened the morning of Dec. 31, 2021 and my car still has not been evaluated by Mercedes. I was taken to the ER and spent 3 days in the hospital.”
NHTSA complaint #11452817, 2021 · crash · 1 injury(ies)

“points: ⸻ While driving, the vehicle displays the warning “Active Brake Assist Functions Limited – See Operator’s Manual.” The message appears during normal driving and does not go away. This warning indicates that the automatic emergency braking / Active Brake Assist system is limited or disabled, reducing a critical safety feature designed to help prevent or mitigate collisions. This creates a safety risk because the vehicle may not automatically brake in an emergency situation. The warning appeared suddenly while driving, with no visible obstructions, weather conditions, or damage to se…”
NHTSA complaint #11710171, 2026

“The component that failed was the fuel injector and spark plug. A few months prior to this incident, I was making a left hand turn, when the accelerator completely gave out. I was making the left on a blinking yellow arrow, luckily the on coming car was not coming at me fast or I would've been in an accident due to the accelerator failing. I had to pull over, turn the car off and then back on to reset it. I was told by the dealership service center that they could not find anything and that there have been no complaints or recalls. After about 8 months of owning the vehicle, it started to have…”
NHTSA complaint #11490902, 2022

Steering 3 1 crash 2 injury

“While driving on the turnpike without warning my steering locked and I lost control of my car.”
NHTSA complaint #11423100, 2021 · crash · 2 injury(ies)

“Uneven wear pattern.The wear often occurs on inner shoulder of the tires 5k to9k miles,which can be dangerous tire can wear down to belts on inside edge while the outer tread still looks fine. i have brought this to dealership multiple time with NO FIX but to sale me new tires and alignments.I have spoke to multiple owners of 2020 mercedes c63 and they have the same problem. This is a safety issue and has left my wife and kids on the side of freeway broken down.”
NHTSA complaint #11697729, 2025

“Over the past month, my 2020 Mercedes-Benz C300 has been experiencing unexpected and increasingly concerning issues with the steering. These problems began suddenly and without any prior warning signs. Initially, the steering has been making grinding sounds more usual, particularly at lower speeds and when making tight turns. Over the following weeks, the issue became more pronounced, with occasional instances of the steering wheel resisting movement or feeling delayed in its response. At times, it feels as if the power steering system is intermittently failing or underperforming. There have b…”
NHTSA complaint #11667088, 2025

Visibility 3

“The contact owns a 2020 Mercedes-Benz C300. The contact stated that a section of the roof near the top of the windshield, between the sunroof, had detached and flown off the vehicle while driving 30 MPH in bumper-to-bumper traffic. The driver was able to grab the portion of the rubber gasket and pulled it into the vehicle through the driver’s side front window. The roof was in three pieces. The contact turned on the hazard lights and was able to pull over safely to the side of the roadway. There were no warning lights illuminated. The contact was concerned about the failure potentially causing…”
NHTSA complaint #11678311, 2025

“The contact owns a 2020 Mercedes-Benz C300. The contact stated while driving 55 MPH, the sunroof exploded without impact and glass fragments fell inside on the rear seats of the vehicle. The vehicle was taken to the dealer and the contact was informed that the sunroof needed to be replaced. The vehicle was not repaired. The contact stated that the failure had occurred twice. The manufacturer was contacted and stated that the vehicle was not under recall. No further assistance was provided. The failure mileage was 34,000.”
NHTSA complaint #11526868, 2023

Latches/Locks/Linkages 2

“The issue is that the trunk lid closes abruptly and unintentionally. On Saturday, February 3, 2024, as I was putting a shopping bag in the trunk of my car, the trunk lid closed abruptly without my pressing the close button and hit my forehead. The impact was such that my eyeglasses flew off my face and hit the ground. The pain was severe and two days later, I still have pain. While there was no tear to the skin, there's a bump on my forehead and is still painful. The head injuries generally do not show adverse symptoms until months after the incident. I called the Mercedes Benz corporation a…”
NHTSA complaint #11569947, 2024

“TL* THE CONTACT OWNS A 2013 MERCEDES-BENZ C300. THE CONTACT STATED THAT THE DOOR HANDLE WAS FRACTURED INTERNAL AND UNABLE TO BE OPENED FROM INSIDE OF THE VEHICLE. THE CONTACT STATED THAT HER SON WAS LOCKED INSIDE THE VEHICLE AND UNABLE TO EXIT. THE CONTACT INFORMED HER SON TO USE THE KEY FOB TO EXIT THE VEHICLE. THE VEHICLE WAS TAKEN TO AN INDEPENDENT MECHANIC AND WAS DIAGNOSED WITH A FRACTURED INTERNAL DOOR PANEL WHICH CAUSED THE DOOR HANDLE TO BECOME INOPERABLE. THE VEHICLE WAS NOT REPAIRED. THE MANUFACTURER WAS NOT CONTACTED OR INFORMED OF THE FAILURE. THE APPROXIMATE FAILURE MILEAGE WAS 10…”
NHTSA complaint #11362268, 2020

Tires 2

“BOTH the front tires in my 2020 Mercedes C300 developed sudden belt separation while driving at highway speed this past weekend. These tires were installed by Mercedes of Delray Beach Florida as part of my CPO vehicle purchase in September of 2022 and have less-than 20K miles on them. Tires are Continental ProContact size 225/45 R18 and marked M+S as well as MOE. The vehicle received a routine four-wheel alignment as part of my annual servicing in July 2025 by Mercedes of Fort Pierce, and no indication of any tire issue was mentioned. Tire pressures have been consistently checked monthly and…”
NHTSA complaint #11689319, 2025

“OEM tires that the Mercedes Benz dealership diagnosed as having shifted belts. 245/40 R18”
NHTSA complaint #11474717, 2022

Vehicle Speed Control 2

“The contact owns a 2020 Mercedes-Benz C300. The contact stated that while at a stop, the vehicle failed to accelerate as intended. There was no warning light illuminated. The dealer was not contacted. The vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure and referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 100,000.”
NHTSA complaint #11731613, 2026

“TL* THE CONTACT OWNS A 2020 MERCEDES BENZ C300. THE CONTACT STATED THAT WHILE DRIVING AT A HIGH RATE OF SPEED, THE VEHICLE WOULD ABRUPTLY SLOW DOWN ONCE THE TRAFFIC SIGN READER FEATURE ACTIVATED INDEPENDENTLY WITHOUT WARNING. THE CONTACT STATED THAT ONCE A TRAFFIC SIGN ON THE ROAD WOULD INDICATE A CERTAIN SPEED LIMIT, THE VEHICLE WOULD THE SPEED LIMIT SIGN AND AUTOMATICALLY ADJUST THE VEHICLE'S SPEED TO THE SPEED LIMIT READING. THE CONTACT INITIALLY CALLED MERCEDES-BENZ OF BONITA SPRINGS(14610 TAMIAMI TRAIL N, NAPLES, FL 34110) WHERE HE WAS INFORMED TO CALL THE MANUFACTURER. THE MANUFACTURER…”
NHTSA complaint #11339325, 2020

Lane Departure 1

“ON A NUMBER OF OCCASIONS, I HAVE RECEIVED AN AUDITABLE WARNING, AND A RED LIGHT ON THE DASH THAT DISAPPEARS AS QUICKLY AS IT HAPPENS. I CANNOT CONTRIBUTE ANY CAUSE FOR THE WARNING AND THERE ISN'T ANY RESIDUAL INFORMATION ABOUT THE SOURCE OF THE WARNING.”
NHTSA complaint #11385957, 2020

Service Brakes 1

“points: ⸻ While driving, the vehicle displays the warning “Active Brake Assist Functions Limited – See Operator’s Manual.” The message appears during normal driving and does not go away. This warning indicates that the automatic emergency braking / Active Brake Assist system is limited or disabled, reducing a critical safety feature designed to help prevent or mitigate collisions. This creates a safety risk because the vehicle may not automatically brake in an emergency situation. The warning appeared suddenly while driving, with no visible obstructions, weather conditions, or damage to se…”
NHTSA complaint #11710171, 2026

Suspension 1

“Uneven wear pattern.The wear often occurs on inner shoulder of the tires 5k to9k miles,which can be dangerous tire can wear down to belts on inside edge while the outer tread still looks fine. i have brought this to dealership multiple time with NO FIX but to sale me new tires and alignments.I have spoke to multiple owners of 2020 mercedes c63 and they have the same problem. This is a safety issue and has left my wife and kids on the side of freeway broken down.”
NHTSA complaint #11697729, 2025

Wheels 1

“The contact owns a 2020 Mercedes-Benz AMG C43. The contact stated while driving 65 MPH, the tire pressure warning light illuminated. The contact took the vehicle to a tire center and was informed that the front passenger’s side rim cracked, causing the tire to deflate. The tire center repaired the original rim. The failure recurred with the rear driver’s and rear passenger’s side rims. The contact stated that the wheels were the original wheels on the vehicle. The vehicle was not diagnosed after the most recent failure. A dealer was not contacted. The manufacturer had not been informed of the…”
NHTSA complaint #11522258, 2020