2012 Mercedes-Benz C 300 Problems
Owner-reported complaints filed with NHTSA, grouped by component
Data refreshed
What this page shows
Everything below is an owner-reported complaint submitted to NHTSA about the 2012 Mercedes-Benz C 300, grouped by the component NHTSA recorded on the report. These are not confirmed defects, and they are not recalls. NHTSA does not verify most reports before publishing them, and a category with more reports in it is not evidence that a part is defective.
Complaints are reports submitted by owners and drivers to NHTSA. They are not verified and do not establish that a defect exists.
Reports by component
Ranked by how many owner reports name each component category
- Airbags11437.1%
- Suspension6822.1%
- Body & structure5317.3%
- Brakes154.9%
- Electrical123.9%
- Fuel system113.6%
- Steering82.6%
- Engine51.6%
- Powertrain (other)51.6%
- Exterior lighting41.3%
- Other / unspecified41.3%
- Visibility31.0%
- Driver assistance20.7%
- Seat belts10.3%
- Interior & seats10.3%
- Tires & wheels10.3%
Percentages are of component mentions. A single complaint can name more than one component, so these do not sum to the total complaint count.
Each component in detail
What the reports in each category say, in the owners' own words
Airbags
Reports naming the air-bag system — deployment behaviour, inflators, sensors and warning lights.
From owner reports, verbatim
I was driving normally last week when the driver's head restraint system (known by Mercedes as Neck Pro) unexpectedly and without warning blew at my head. The noise was very loud, and the headrest slammed against my head. Luckily, I was driving approximately 20-25 miles per hour, daytime, on a residential street without too many other vehicles. I was able to pull over to investigate what happened and ensure I wasn't injured and did not collide with any objects in the road. If this had happened on the highway at highway speeds with a less attentive driver, I could see this potentially resulting in a major collision. The road was fat, no bumps, weather was clear. There is no reason why this happened. From what I can tell, the system looks like it failed (plastic clips broke off) and the system did not intentionally deploy. It has not been repaired and is available for inspection. I have not taken it to the dealership for review. The vehicle is in perfect condition with no warnings. It very recently passed Maryland state inspection.
3 signal Signal light comes one saying abs, another SRS MALFUNCTION, also crushed control inoperable. Car will come one as normal next day car comes on no lights not 1 button work turn signals didn’t work then my car fan came on in the engines the also the when they the electric isn’t working i have to manually shift the gear
Suspension
Reports naming suspension components — springs, struts, shocks, control arms and related hardware.
From owner reports, verbatim
I have a rust free, relatively lower mileage car I bought for my teen daughter. Despite being such a clean car the rear subframe has rusted and rear suspension has broke off while driving, hitting the fuel tank and is unstable. We avoided an accident but the car is not drivable.
Mercedes of Danbury replaced the rear sub frame CODE 3441 47, since my mechanic (Newtown Auto Repair) told me that the Front subframe is in real bad shape, rotten/rusted, that it is dangerous to drive the car in this condition since the wheel and steering components are part and attached to it, the car would be out of control and all over the road any of these components fail and pull / brake away from the rusted out Sub Frame. When I brought the car in was under the impression that Mercedes Benz would replace front and back Sub Frames. But now they informed me of only recall on rear subframe, rear subframe will let go wheels will collapse, front controls the car and failing could kill people and total the car. frames.
Body & structure
Reports naming the vehicle structure, frame, body panels, doors, hood and trim.
From owner reports, verbatim
Mercedes of Danbury replaced the rear sub frame CODE 3441 47, since my mechanic (Newtown Auto Repair) told me that the Front subframe is in real bad shape, rotten/rusted, that it is dangerous to drive the car in this condition since the wheel and steering components are part and attached to it, the car would be out of control and all over the road any of these components fail and pull / brake away from the rusted out Sub Frame. When I brought the car in was under the impression that Mercedes Benz would replace front and back Sub Frames. But now they informed me of only recall on rear subframe, rear subframe will let go wheels will collapse, front controls the car and failing could kill people and total the car. frames.
Rear subframe rotted out and broke due to corrosion. Rear crossmember is broken and needs replaced. My safety as well as the safely of other was put at risk. Loss of control at high speed could have been deadly. Luckily, I wasn’t going very fast at the time of incident or else who knows what would have happened to me or bystanders. Independent service center inspected and confirmed that incident was due to corrosion in the rear. They informed me of the extended warranty (20 years, unlimited miles) on 2008-2015 C300 models for this particular issue as my safety and the safety of others was put at risk. There were some symptoms leading up to the incident. At the time of braking the car would become unstable and feel skittish in the rear. It felt as if the rear was sliding to one side. The vehicle would also make some metal clinking noises at sharper turns. The symptoms had been more frequent in the prior 2-3 months of incident. The vehicle has been inspected and diagnosed by one shop and is currently getting a second opinion from another independent service center.
Brakes
Reports naming service brakes, the antilock braking system, brake hoses, master cylinders or the parking brake.
From owner reports, verbatim
The subframe has developed extensive rust and corrosion, which I believe is a result of faulty manufacturing. This corrosion has severely compromised the structural integrity of the subframe, posing a serious safety risk. The corrosion appears to be inherent to the materials or design used in the manufacturing process, leading to the rapid deterioration of the subframe. There are also no warning lights or failure indicators for this issue. As a result, the subframe is at risk of collapsing, which could cause catastrophic failure of the vehicle's suspension and steering systems. This situation creates an immediate danger to both the occupants of the vehicle and others on the road.
Brake line corrosion
Electrical
Reports naming the electrical system — wiring, battery, charging, control modules, infotainment and electrical accessories.
From owner reports, verbatim
I was replacing rear tail light bulb. Now I'm getting an error message on instrument cluster. I tried to fix the issue but couldn't do to the fact the wiring harness has melted. Mercedes Benz had a recall back in 2013 saying this is a safety issue. No recall for our car.
The contact owns a 2012 Mercedes-Benz C300. The contact stated that after opening the sunroof and then attempting to close the sunroof, the sunroof failed to fully close. The contact had to open and close the sunroof several times before the sunroof closed. Additionally, the contact stated that there was water entering the vehicle from the sunroof which caused electrical failures. The contact stated that the vehicle was drivable, but the "Anti-Theft" warning light illuminated. The contact stated that several other warning lights were later illuminated, and the vehicle would not start. The contact had the vehicle towed to a dealer who diagnosed the vehicle and determined that water had damaged the driver’s side electrical wiring harness. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 169,000.
Fuel system
Reports naming fuel storage or delivery — tanks, pumps, lines, injectors and fuel leaks.
From owner reports, verbatim
Vehicle: 2012 Mercedes-Benz C300 4Matic Sport Problem Component: Fuel / Propulsion System Safety Issue Description: My 2012 Mercedes-Benz C300 developed a serious fuel tank leak at approximately 106,460 miles which created overwhelming gasoline fumes and rendered the vehicle unsafe to operate. The gasoline fumes were extremely strong and entered the passenger area. The fumes were severe enough that I became physically overwhelmed from the gasoline exposure and discarded clothing due to gasoline contamination and odor. A local repair facility identified the leaking fuel tank. I was informed the replacement fuel tank was allegedly on extended backorder through Mercedes-Benz channels. Because the vehicle was unsafe to drive and replacement parts were allegedly unavailable for several months, I was forced to tow the vehicle from [XXX] to [XXX] at my own expense in order to locate a repair facility that could obtain a replacement fuel tank and safely repair the vehicle. The repair invoice states: “Installed used lt fuel tank incl switchover fuel pumps replace section of steel fuel line front of tank from lower braided line.” I am submitting this complaint due to: serious gasoline leak safety concerns, severe gasoline fume exposure, potential fire hazard, and the alleged extended unavailability of replacement fuel tanks. Mercedes-Benz USA Case Number: 22302114 INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
The contact owns a 2012 Mercedes-Benz C300. The contact stated the fuel tank was emitting a fuel odor. The contact stated that the fuel odor was extremely strong and could be smelled inside the residence while the vehicle was parked in the garage. There were no warning lights illuminated. The vehicle was taken to a Certified Mechanic, who diagnosed that the leak was coming from the top of the fuel tank; however, the mechanic was unable to specify the cause. The vehicle was towed to the dealer, but the vehicle was not diagnosed. The vehicle was not repaired. The contact became aware of NHTSA Campaign Number: 12V557000 ( Fuel System, Gasoline) online; however, the VIN was not included. The manufacturer was informed of the failure and informed the contact that the VIN was not under recall. The failure mileage was approximately 98,000.
Steering
Reports naming the steering system — racks, columns, power-steering assist and steering linkage.
From owner reports, verbatim
My 2012 c300 has a rotted rear subframe making the car not able to be driven. It has major ,life threatening, costly damage and this issue already has a recall all over the world but not in the United States. If I can get the assistance to pay this repair, it will be gladly appreciated.
Rear Sub Frame Assembly failure. It is available for inspection upon request. Vehicle rear end begins to wobble at speeds above 40 mph. The issue causes steering to become more complicated and the vehicle veers sharply while braking. This issue makes all C Class vehicles with this Sub Frame Assembly extremely unsafe, especially at highway speeds. Vehicle has been inspected by the authorized Mercedes Benz dealership in Indianapolis, IN. Service Advisor stated it's "amazing" that there hasn't been a recall issued yet. Based on this body style there have been roughly 320,000 of these C-Class vehicles sold. If the NHTSA truly cares about safety, they will launch an investigation into this matter. There are no warning lamps or messages that appear prior to this failure.
Engine
Reports naming the engine itself — including stalling, misfires, oil consumption, cooling and internal engine components.
From owner reports, verbatim
ON A 4 LANE BOULEVARD CLOSE TO HOME I PULLED OUT TO PASS A SLOW CAR AND NOTICED A CAR COMING UP FROM BEHIND AT A HIGH RATE. I PUSHED THE ACCELERATOR TO THE FLOOR, THE CAR STARTED ACCELERATING THEN LOST ALL POWER. THE ENGINE HAD CUT OFF AND ALL THE DASH LIGHTS WERE ON. I ROLLED TO A STOP, AS FAR OFF THE ROAD AS I COULD. AFTER A FEW SECONDS I RESTARTED THE CAR AND DROVE HOME. SIMILAR INCIDENTS CAN BE FOUND ON YOU TUBE BUT NOT FOR A C300. THE ONES I FOUND WERE FOR A C240 MERCEDES. THEY SAY THE PROBLEM IS DUE TO THE COMPUTER SHUTTING DOWN THE ENGINE BECAUSE IT CAN'T PROPERLY BALANCE THE FUEL TO AIR RATIOS. THIS SEEMS LOGICAL BECAUSE I HAVE NEVER HAD TO ACCELERATE LIKE THIS BEFORE. THIS COULD HAVE BEEN CATASTROPHIC IF I WOULD HAVE BEEN PULLING OUT INTO FAST TRAFFIC ON A BUSY HIGHWAY AND THE ENGINE SHUTS DOWN. NOW I 'M AFRAID IT WILL HAPPEN AGAIN. I JUST DON'T KNOW WHEN. ALL I CAN DO IS TRY NOT TO PRESS DOWN ON THE ACCELERATOR TOO FAR. THE DEALER SAID NOTHING WAS IN THE CAR'S COMPUTER MEMORY SO HE COULDN'T DO ANYTHING. I'M SUSPICIOUS OF THAT BECAUSE IF THEY ADMIT THERE IS A PROBLEM THEN THEY WOULD BE EXPECTED TO FIX IT. I THINK THEY KNOW THERE IS A PROBLEM BUT DON'T KNOW WHAT TO DO ABOUT IT.
STEERING WHEEL LOCK AFTER VEHICLE IS SHUT DOWN. WHEN YOU RETURN TO THE VEHICLE INSERT THE KEY THE INSTRUMENT CLUSTER, SPEEDO, STEERING WHEEL IS UNRESPONSIVE WHICH WILL NOT ALLOW YOU TO TURN THE ENGINE. THIS SHOULD BE A RECALL IT'S A ELECTRONIC STEERING LOCK THAT FAILS ON SEVERAL MERCEDES BENZ CAUSING THE OWNER TO TOW THE VEHICLE TO THE DEALERSHIP FOR A 2,000 DOLLAR REPAIR. IT HAPPENS SEVERAL TIMES BEFORE IT COMPLETELY FAILS.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Powertrain (other)
Powertrain reports that are not specifically the engine or transmission — driveshafts, axles, transfer cases and differentials.
From owner reports, verbatim
vehicle sub-frame is cracked rusted corroded.
The left rear weld of the subframe on my 2012 C300 4matic has rotted through and appears to be a manufacture's part defect. I found out about this issue from a brake inspection and told it is a safety concern, which Mercedes Benzes is aware of but has no recalls for the defect.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Exterior lighting
Reports naming headlights, tail lights, turn signals and other exterior lighting.
From owner reports, verbatim
The contact owns a 2012 Mercedes-Benz C300. The contact stated that while the vehicle was parked, the passenger’s side rear taillight was inoperable. The vehicle was taken to a local dealer but was not diagnosed or repaired since the VIN nor the model year was not included in NHTSA Campaign Number: 14V177000 (Exterior Lighting). The manufacturer was not made aware of the failure. The failure mileage was approximately 180,000.
The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving 35 MPH, he smelled a rubber burning odor. A message indicating that the turn signal was inoperable was displayed. The contact stated that he pulled to the side of the road and inspected the vehicle. The contact noticed that there was smoke coming from the rear passenger's side taillight. The contact stated that he opened the taillight panel and noticed that the interior and the bolt had melted. The contact was able to continue driving. The contact related the failure to Mercedes-Benz Campaign Number: 2014050001; however, the dealer informed the contact that the VIN was not included in the recall. The vehicle was not repaired. The manufacturer was notified of the failure and informed the contact that the VIN was not included in the campaign. The failure mileage was approximately 30,000.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Other / unspecified
Reports whose component NHTSA recorded as unknown, or that do not map to one of the categories above.
From owner reports, verbatim
My 2012 c300 has a rotted rear subframe making the car not able to be driven. It has major ,life threatening, costly damage and this issue already has a recall all over the world but not in the United States. If I can get the assistance to pay this repair, it will be gladly appreciated.
Rear driver side wheel was making a clicking noise leading us to believe there was an issue with the strut and/or shock. Due to the nature and severity of the noise, we took the vehicle to our mechanic ASAP. Upon inspection, mechanic identified that the sub-frame had completely rusted through which could lead to other catastrophic issues making vehicle no longer safe to drive unless repaired. Due to the age of the vehicle being 11 years old, the cost to repair was almost the value of the vehicle basically making this a complete loss. I understand that Mercedes Benz has extended the warranty to 20 years for this issue for other models identifying that it is a design/parts defect but not the C300 although I have found that this is also an issue for this model.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Visibility
Reports naming windshields, glass, wipers, defrosters and mirrors.
From owner reports, verbatim
The contact owns a 2012 Mercedes-Benz C300. The contact stated that after opening the sunroof and then attempting to close the sunroof, the sunroof failed to fully close. The contact had to open and close the sunroof several times before the sunroof closed. Additionally, the contact stated that there was water entering the vehicle from the sunroof which caused electrical failures. The contact stated that the vehicle was drivable, but the "Anti-Theft" warning light illuminated. The contact stated that several other warning lights were later illuminated, and the vehicle would not start. The contact had the vehicle towed to a dealer who diagnosed the vehicle and determined that water had damaged the driver’s side electrical wiring harness. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 169,000.
It is a wide-spread issue and commonly known issue that when the car battery is replaced in Mercedes-Benz vehicles, the climate control stops working, as well as the blower. The safety issues: •Car battery needed to be replaced during non-daylight hours during the winter. •Climate control stopped working immediately upon battery replacement, and issues with blower arose. •I drove home in the dark, during winter, without the ability to defrost my windows. A quick Google search for this issue will uncover an abundance of consumer complaints and common themes regarding this issue.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Driver assistance
Reports naming forward-collision avoidance, lane keeping, back-over prevention, cruise control and related electronic driver-assistance systems.
From owner reports, verbatim
SENSOR FOR SIDE VIEW MIRRORS CONTINUE TO MALFUNCTION PROVIDING INACCURATE INFORMATION AND LOCKING ON (LIGHT) AND NOT SHOWING WHEN NEEDED
TL* THE CONTACT OWNS A 2012 MERCEDES BENZ C300. WHILE STOPPED AT A RED LIGHT WITH THE BRAKE PEDAL DEPRESSED, THE VEHICLE ACCELERATED EXTREMELY FAST INTO AN INTERSECTION. AS A RESULT, THE CONTACT'S VEHICLE WAS STRUCK BY ANOTHER VEHICLE ON THE FRONT DRIVER'S SIDE DOOR. THE CONTACT SUFFERED A BROKEN CLAVICLE, A BRUISED ANKLE, CHEST, AND BACK. MEDICAL ATTENTION WAS RECEIVED. A POLICE REPORT WAS FILED. THE VEHICLE WAS TOWED TO THE POLICE IMPOUND LOT. THE MANUFACTURER WAS NOT MADE AWARE OF THE FAILURE. THE APPROXIMATE FAILURE MILEAGE WAS 40,000. UPDATED 7/1/15*CN
Too few reports in this category for a page of its own — they appear in the full complaint list.
Seat belts
Reports naming seat belts, buckles, retractors and pretensioners.
From owner reports, verbatim
TL* THE CONTACT OWNED A 2012 MERCEDES-BENZ C300. WHILE DRIVING AT AN UNKNOWN SPEED, THE CONTACT'S VEHICLE REAR ENDED ANOTHER VEHICLE. THE AIR BAGS DID NOT DEPLOY AND THE SEAT BELT PRETENSION DID NOT FUNCTION. A POLICE REPORT WAS FILED. THE VEHICLE WAS DESTROYED AND TOWED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE. THERE WAS ONE INJURY THAT REQUIRED MEDICAL ATTENTION. THE CONTACT SUSTAINED SHORT TERM MEMORY LOSS, A SEIZURE, AND LIVER DAMAGE. THE CONTACT HAD TO REMAIN HOSPITALIZED FOR FIVE DAYS. THE FAILURE MILEAGE WAS 66,000.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Interior & seats
Reports naming seats, latches, locks, linkages and interior fittings.
From owner reports, verbatim
The contact owns a 2012 Mercedes-Benz C300. The contact stated that the front driver's side interior door handle was fractured. The contact was unable to open the door from inside the vehicle. An independent mechanic inspected the vehicle and referred the contact to the manufacturer for assistance. The dealer was not notified of the failure. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 95,000.
Too few reports in this category for a page of its own — they appear in the full complaint list.
Tires & wheels
Reports naming tires, wheels, hubs, or the tire-pressure monitoring system.
From owner reports, verbatim
I HAVE A MERCEDES BENZ C300 WITH 16,300 MILES ON IT. THE VEHICLE CAME WITH CONTINENTAL, CONTIPRO, 225/45 R17 91H TIRES ON IT TWO TIRES ON THE LEFT SIDE OF THE CAR HAVE DEVELOPED BUBBLES ON THEM AND WILL HAVE TO BE REPLACED. THE TIRES ON THE RIGHT SIDE WILL HAVE TO BE INSPECTED SINCE THEY MAY HAVE BUBBLES ON THE INSIDE. I HAVE JUST READ MANY COMPLAINS ABOUT THESE TIRES AND FEEL THEY ARE DANGEROUS AND SHOULD BE RECALLED. *TR
Too few reports in this category for a page of its own — they appear in the full complaint list.
Higher-selling and older vehicles accumulate more reports. Counts are not failure rates and are not directly comparable between vehicles that sold in very different numbers.
Elsewhere on this vehicle
Data sources
- NHTSA Office of Defects Investigation — owner-reported complaints and the components recorded on them
Data on this page last refreshed .