2016 Mercedes-Benz C300 Problems

What owners report

Owners of this model year most often report a gasoline smell in and around the cabin, which complaints trace to leaking fuel lines, the fuel rail or injectors, and report panoramic sunroof glass or panels that detach or shatter while driving. Engine stalling and loss of power also appear, sometimes at low mileage, while several electrical faults are described on cars with little mileage. Fuel-odor reports tend to cluster higher in the mileage range than the engine and electrical complaints.

1. 1
   Fuel system

   Fuel odor from leaking fuel lines and connections

   • 66 complaints (23%)
   • median 56,500 mi at 5.4 yrs old (18 state mileage)
   • 1 mention a crash, fire or injury
   • owner-quoted repair $1,288 (median of 5 quotes)
   • filed 2016–2026

   Owners describe a strong gasoline smell inside the cabin, outside the car, and through the vents, often most noticeable after a cold start, when the heater or A/C is running, or when the tank is full. Complaints say dealers and independent shops identified leaking high-pressure fuel lines, hose clamps, the fuel rail or injector connections, and in some cases a fuel pump leak. Several owners report that the repair was quoted as not covered by warranty or was described as a wear item, and some say the odor returned or persisted after other work such as a cabin filter change. Mostly reported between roughly 17,000 and 90,000 miles, with several owners noting the odor is worse in cold weather or after starting the engine.

   Recall 21V9610001 related service bulletin

   What to check: Ask whether the high-pressure fuel lines, clamps, rail and injectors have been inspected or replaced, and check for a fuel smell under the hood and in the cabin after a cold start. A service bulletin describes diagnostic guidance for implausible fuel gauge readings rather than a fix for the odor.

   2 excerpts from owner complaints in NHTSA records

   “2016 MB 300 C, AWD at 87000 miles started giving gas fuel smell when parked in our garage after driving. I took to a local Foreign Car Repair facility and they found a fuel leak at the fuel injector pump. The mechanic changed the Fuel Injector Pump (Bosch) at a total cost of $745.31. Since the change in the pump, the smell has stopped and I feel safe. Who is responsible to reimburse this cost to me?”

   NHTSA complaint #11444351, filed 2021-12, 87,000 miles

   “2016 MERCEDES BENZ C300. When I start the car , you smell gas inside and outside of the car. Also the fumes come the vent when the heat is turned on. I have approximately 69,700 miles on my car”

   NHTSA complaint #11498933, filed 2022-12, 69,700 miles
2. 2
   Body and structure

   Panoramic sunroof glass or front panel detaching

   • 51 complaints (18%)
   • median 40,600 mi at 5.1 yrs old (17 state mileage)
   • 3 mention a crash, fire or injury
   • owner-quoted repair $2,000 (median of 5 quotes)
   • filed 2017–2026

   Complaints describe the glass panel in front of the panoramic sunroof or the sunroof glass itself detaching or shattering while driving at highway speed, sometimes with no impact from another object. Owners report the sunroof then failing to open or close, or the glass lifting and flying off, and say the adhesive bonding or plastic rail clips were blamed. Some owners state their vehicle was not included in a related recall despite showing the same failure. Reported from as little as 17,000 miles up to about 73,000 miles, often at highway speeds and in some cases during rain.

   Recall 23V854000Recall 21V197000Recall 16V087000

   What to check: Inspect the front fixed panel and sunroof glass for loose or lifted edges, check that the sunroof opens and closes smoothly, and ask whether any related roof-panel recall was performed on the vehicle.

   2 excerpts from owner complaints in NHTSA records

   “I was driving down the freeway at approximately 65 MPH and the panoramic sunroof on my mercedes C300 exploded. I say exploded because nothing struck the glass and most of the glass blew out and off the car, not in. The sunroof was closed at the time, so there was no wind pressure. After I stopped, you can even see where the glass remaining is sticking up, not down. The shade was open so glass did fall into my car, cutting my arm. …”

   NHTSA complaint #11047852, filed 2017-11, 17,000 miles

   “While driving on the highway, I heard a loud noise that, on first impression, LED me to believe someone fired a gunshot at and struck my vehicle. Upon looking up, I immediately noticed it was not a gunshot but instead the glass to the front portion of my panoramic sunroof had spontaneously shattered and flew completely off the vehicle. This flying glass flew directly backwards and could have posed a deadly result for the numerous drivers traveling behind me. …”

   NHTSA complaint #11386655, filed 2021-01, 40,000 miles
3. 3
   Engine

   Engine stalling, loss of power and check engine light

   • 101 complaints (35%)
   • median 50,050 mi at 5.1 yrs old (28 state mileage)
   • 4 mention a crash, fire or injury
   • owner-quoted repair $2,300 (median of 19 quotes)
   • filed 2016–2026

   Owners describe the check engine light coming on and the car losing power or stalling, in some cases on the freeway or while accelerating from a stop. Complaints mention codes pointing to the crankcase ventilation regulator valve, and some say the dealer quoted an engine replacement or a costly tear-down. Others report rough running, a knocking sound, or the engine refusing to restart after a shutdown. Reported from very low mileage up to around 57,000 miles, with several cases between 29,000 and 52,000 miles.

   1 related service bulletin

   What to check: Ask for service records showing whether the crankcase ventilation regulator valve has been addressed, and have a pre-purchase scan done for stored engine fault codes. A service bulletin describes a check engine light with a crankcase ventilation valve fault code.

   2 excerpts from owner complaints in NHTSA records

   “I bought a new 2016 c-class mercedes benz . I had the car for less than 24 hours when the engine light came on. I immediately took the vehicle in and was told that they do not have a fix for the problem. It is a problem with the ambient airflow. The engine does not work properly, causing a rough ride. When trying to accelerate the engine will stall and then shoot forward.”

   NHTSA complaint #10850806, filed 2016-03, 60 miles

   “2016 C300 4matic at about 50k miles, check engine light came on and then as I was driving on the freeway the car just stopped accelerating in the middle of the freeway and had to take my car to the side and towed it to the dealer in west covina. Luckily there was no one on the freeway since it was early sunday morning. Dealer is now saying the car might need engine replacement which will cost me $20k but they want $3000 to do a tear down to make sure. …”

   NHTSA complaint #11388420, filed 2021-01, 52,000 miles
4. 4
   Electrical system

   Dashboard blackout and unexpected electrical behavior

   • 21 complaints (7%)
   • median 11,000 mi at 1.8 yrs old (9 state mileage, few)
   • 4 mention a crash, fire or injury
   • filed 2016–2026

   Owners describe the instrument cluster or dashboard going completely dark for extended periods, sometimes while driving, and being told by the dealer that the vehicle was downloading software. Other complaints describe the car unlocking itself and starting without driver input, and a start/stop stall where the engine would not restart at a stoplight. Reported at low mileage, generally under about 43,000 miles, including a case under 30,000 miles.

   Recall 21V058000Recall 17V114000

   What to check: Ask whether any software or starter-related recall campaigns were completed, and watch for repeated cluster blackouts or unusual door locking and starting behavior during a test drive.

   2 excerpts from owner complaints in NHTSA records

   “On four occasions, the electronic dashboard goes completely black and will stay that way for quite sometime. The dealer told me that the vehicle is 'downloading software', but this has happened on the highway without any warning from m-b. It happens after I park it and then restarted it.”

   NHTSA complaint #11296803, filed 2020-01, 29,000 miles

   “C300 anti collision sensor malfunction light displayed and loss engine power for several seconds. The car was traveling aprox 20 MPH at the time on city street. Then power resumed, the warning light went out. Mercedes-benz of temecula, ca could not find a problem. Workorder 229423, 9/13/16”

   NHTSA complaint #10906348, filed 2016-09, 900 miles

Buying note. Check for a fuel smell after a cold start and confirm whether fuel-line work has been done, and inspect the panoramic roof panels and sunroof operation carefully. Ask for a full service history and a scan for stored engine and body fault codes, since several reported faults appear at low mileage and some related recall campaigns may not cover every vehicle built.

Summary written with AI from a sample of 60 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.