My car is the 2015 Mercedes- benz (MB) c 300 4MATIC. The Check engine light is on and off for some months as initially MB dealer said that it's likely due to gas cap defects so we replaced the gas cap. After that, the engine light is still on and off. MB dealer now said $1,760 to replace crankcase vent value and $2870.55 to repair the front differential leaking/reseal. It will cost me a total of $ $4630.55 +tax to repair. The car has only 70,000 miles and kept good maintenance frequently. Right now my car is not safe to drive it so why this car is broke down so quickly. That is not acceptable to us.

- Glastonbury, CT, USA

Mercedes Benz via American Service Center in Arlington, VA regarding the service they performed on my 2015 C300 W4 4Door Sedan AWD the following issues have presented: ISSUE: 03MBZZWARN1 ENGINE LIGHT TECH: 901844 PROBLEM: ENGINE HARNESS, ENGINE CONTROL MODULE, CRANKCASE VENT VALVE, AND O2 SENSOR BANK 1 CAUSE: FOUND OIL IN THE ENGINE HARNESS AND ENGINE HARNESS. OIL IS ENTERING THREW [SIC] THE CRANK CASE VENT VALVE. RECOMMEND REPLACING. Approximate miles at the time of this issue: 63,141. Cost of Repair: $8309.58 Yes, the vehicle is available for inspection. Safety concerns: The vehicle is not able to pass an emissions test with the engine light engaged. Per America Service Center in Arlington, VA, which is the only service center that has serviced the vehicle during my ownership, they commented and documented that oil is entering through a vent valve. My additional concerns are: If an odorless fume is passing into the passenger cabin and the vehicle can not pass state emissions these are immediate concerns. The service center advices that I may continue to drive the vehicle. However, I am concerned should the oil fully empty without warning the vehicle may fail while in use on a dangerous roadway due to cause and effect of additional unknown maintenance related operational co-dependent mechanical components.

- Landover, MD, USA

PVC valve shouldn-??t fail and each time it does it is around 2k dollars.

- Caldwell, ID, USA

This occurred after an oil change. it is the P052E code crankcase ventilation code.

- West Hartford, CT, USA

Reported to local dealer and corporate office about the issues with shift module not shifting at random, meaning that the vehicle won't shift from park to drive or reverse, and so forth. The local dealer tried to reprogram the software, but the problem still persists. When plugging in my OBD II & DTC readers, code U0103 appairs which translates to "Lost communication with gear shift control module". My concern with this is that I've had this issue while in traffic, which would make my vehicle a hazard. When it comes to the collision prevention system, the system randomly turns on and off, meaning that when it's needed it might turn on, but when it's not needed it randomly turns on. Once again, addressed this with a local dealer and Mercedes Benz corporate with no avail. My concerns here is that the vehicle could prematurely brake causing an accident or not brake at all causing an accident.

- Topeka, KS, USA

The contact owns a 2015 Mercedes-Benz C300. The contact stated that while driving at various speeds, the vehicle would intermittently fail to accelerate upon the depression of the accelerator pedal. The contact took the vehicle to an independent mechanic where she was informed that the turbo booster was defective. The contact then took the vehicle to another independent mechanic where the oil circulation and turbo booster were replaced. After the repair, the air bag warning light was illuminated. The vehicle was taken back to the independent mechanic where the vehicle was diagnosed with a defective clockspring. The dealer was notified of the failure and informed her that there were no recalls on the vehicle. The manufacturer was notified of the failure and referred her to the NHTSA. The vehicle had yet to be repaired. The failure mileage was unknown. The VIN was not available.

- Milton, FL, USA

MY VEHICLE'S Positive Crankcase ventilation valve NEEDS REPLACING. AFTER RESEARCHING THIS ISSUE FOR A WEEK IM LEARNING THAT THIS IS A VERY COMMON ISSUE WITH MY VEHICLE'S MAKE MODEL AND YEAR AND IS LIKELY TO OCCUR MORE THAN ONE TIME IN THE VEHILES LIFETIME. THE PROBLEM HAS BEEN CONFIRMED BY AN INDEPENDENT SERVICE CENTER I WAS MADE AWARE OF THE ISSUE BY MY VEHICLE'S CHECK ENGIN LIGHT

- Ruther Glen , VA, USA

PVC Pipe to turbo. I am very concerned because this is a reoccurring issue with many owners of C300s. Also, I think it is related to recall number 20V364000 Engine and engine cooling: Engine: Gasoline: Turbo/supercharger. The issue was confirmed by a dealer Check engine light illuminated.

- Ruther Glen, VA, USA

The car has intermittent starting issues more noticeably during eco start / stop process. When car does an eco stop at red light or stop but it is unable to restart consistently (10-20% fail rate). All dashboard lights come on and car is stalled. Car can roll if on a hill. Car can be restarted by turning car on and off manually. Only error code is P1ce200 but the manufacturer suggested steps do no solve problem. Battery, auxillary battery, starter, voltage dip limiter, battery sensor, starter relay were replaced. Delear unable to find problem and says all software is up to date.

- Hazlet, NJ, USA

The 7 speed transmission shifts very hard from 1 gear to 2 gear to 3 gear. From 3 gear all the way to 7 gear is very smooth. Also the same way around when you downshift from 3 gear to 2 gear to 1 gear. The slowing down is very harsh and it looks like the transmission doesn't understand that the car is going to a full stop. All the power and speed cut down a few seconds before full stop. I have personally tried to do the reset with key and pedal trick but it only works for a day or two and goes right back to the rough shifting.

- Bronx, NY, USA

On February 9th, during my morning commute on the interstate the car lost power to the drivetrain. Message that displays was "collision assist plus inoperative" along with cruise control inoperative. With an amber esp light illuminated, there was no engine light on. When this message appeared the car would no longer accelerate (limp mode). In avoidance to being in a rear end collision I quickly pulled over, turned off the car and turned back on. Inoperative message, limp mode and esp light was cleared. I called dealer to notify. My thought was the battery is a dud (was replaced the day prior), the car needs a software reboot due to the new battery or car was not connected to the "memory saver" correctly. Or the sensors were dirty. So I did the easiest. I washed the car. This problem continued to happen 5-6 times more over the next few days stalling on the freeway at 65-75 mph. Extremely dangerous & life threatening. No engine problems apparent. Seems to be radar or software. This is extremely dangerous while on the highway, I found many other with this same issue on NHTSA. I attached a picture of car showing message with no power. My seatbelt was off as I was on side of road trying to get to gas station. This issue is cleared by turning car on / off. Then it happens again hours or a day later, loss of power at highway speeds. Coast over.

- River Falls, WI, USA

Dont know which category it falls. I bought this car in August 2015. In one week it would not start even. Towed to dealership and they said, the grounding screw was loose. I am so surprised that a car comes out from factory with a loose grounding issue. In the last 2 weeks, the car just stalled at the signal. All lights came up. I had the eco start/stop mode on. This happened 3 times and finally I shut the eco start/stop mode down. It is so dangerous that in heavy traffic, when people are ready to drive on change of signal, the car wont move, people are honking and frustrated and I am too. Looked online and so many people are complaining the same. The whole of dashboard lights up like when a car stalls. This is very dangerous. Anybody waiting behind you can take the pedal from the brake and smash into you. Similarly, for last 2 months, I have noticed that there is a jumping nature when you take leg of the brake at the signal. That scares me as well. From the feel of it, I feel this is primarily a software issue where the computer thinks it is in some mode when it is not or something and shuts everything down as a precautionary measure or something

- Kendall Park, NJ, USA

Was driving on city street, and the collision prevention assist disabled warning sign came on and I lost power to the car. I'm told this is called "limp mode." I tried to pick up speed by pressing throttle to the floor, but got no reaction at all. Then some power came back, but not much. Each time I braked to stop for light or turn this would happen. After I got home I restarted the engine and it seemed normal again. However I was afraid to drive it, especially since in the last six months my power steering also failed, and had it towed to dealer. They ran tests and no code for failure was found. They said they found some software updates which they did. Unfortunately, after I picked up the car from service I saw that my main complaint wasn't even mentioned. Only that I sometimes had problem with collision control warning going off for no apparent reason.

- Raleigh, NC, USA

The contact owns a 2015 Mercedes-Benz C300. While driving at various speeds, the vehicle would independently decelerate with the RPM gauge reading between 4,000-5,000. The failure occurred intermittently. When the vehicle was shut off and restarted, the vehicle returned to normal. The vehicle was taken to the dealer for diagnostic testing; however, the failure could not be duplicated. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was 1,000.

- North Branford, CT, USA

I was driving on a rural back road at 30 miles, the power steering stopped working. A warning appeared saying "malfunction of power steering". I was able to drive home, about one mile, but with great difficulty. I called Mercedes Benz. They sent a tow truck and towed auto to westwood Mercedes in westwood, MA. I was informed it was a software problem and it had been reprogrammed.

- Dover, NH, USA