Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2011 Mercedes-Benz C300 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2011 Mercedes-Benz C300. The contact stated he started to smell an abnormal fuel odor and noticed a spot where fuel had leaked onto the garage floor. The contact stated that the check engine warning light was illuminated. The contact stated that while inspecting the vehicle, he noticed both fuel tank covers were cracked. The contact drove another vehicle to the local dealer and made them aware of the failure. The vehicle was not diagnosed or repaired. Upon investigation, the contact associated the failure with NHTSA Campaign Number: 12V557000 (Fuel System, Gasoline) however, the VIN was not included. The manufacturer had been informed of the failure. The failure mileage was approximately 82,000.
The contact's client owns a 2011 Mercedes-Benz C300. The contact stated that the vehicle's owner had complained of an abnormal fuel odor coming from the vehicle. There was no warning light illuminated. Upon inspecting the vehicle, the contact discovered that fuel was spraying out of the fuel pump onto the exhaust. The contact was able to replace the fuel pump and correct the failure. Upon investigation, the contact discovered NHTSA Campaign Number: 12V557000 (Fuel System, Gasoline) which he linked to the failure. The dealer nor the manufacturer had yet to be notified of the failure. The vehicle had been repaired. The failure mileage was approximately 142,000.
The contact owns a 2011 Mercedes-Benz C300. The contact stated that after refueling the vehicle and driving a short distance, there was a burning odor coming from inside and outside the vehicle. The traction control warning light was illuminated. The contact had taken the vehicle to a certified mechanic who replaced the fuel cabinet. The burning odor persisted. The contact was informed that the failure was related to NHTSA Campaign Number: 12V557000 (Fuel System, Gasoline) however, the VIN was not included. The manufacturer was made aware of the failure. The approximate failure mileage 12,800.
My check engine light came on approximately one month ago. Once tested it indicated a fuel vapor leak. I pulled out of a driveway and a large stream of fuel spilled all over the roadway. Approximately 7 feet in length about 5 inches in width was on the road. I took it to a Mercedes repair shop and they informed me I had a fuel leak and that it was not safe to drive. There was corrosion and rust forming on the tank which seems very odd since the car is garage kept and we don't get much snow in Kentucky. My daughter rides in this car with me and they told me it is very dangerous and needs repaired. If I was to drive over a cigarette we could essentially blow up. I had a second shop look at it and they also informed me I had a fuel leak and would need to replace the fuel tank. …
On 8/3/2023 we could smell a strong gasoline smell inside and outside our 2011 Mercedes C300. We towed the car to a Mercedes specialty repair shop for inspection. The found that the passenger side fuel pump cover (which is a large cylinder assembly actually) was leaking due to cracked plastic. Gas vapors could be detected outside the car, in the trunk, and in the car as the gas tank is right under the back seat. Our mechanic said he had just fixed another Mercedes with the exact same problem. Apparently this is a well known defect and I understand that Mercedes has an extended warranty for later models. We believe the extended warranty should be extended to our 2011 C300 which has only 55,000 miles.
When fuel tank is greater than approximately 3/4 full there is a strong fuel odor that seems to emanate from the rear passenger side of the vehicle; at lesser fuel quantities the odor is not noticeable. On one occasion I detected what appeared to be fuel dripping from underneath the vehicle. Took vehicle to dealership for troubleshooting and was informed "fuel leaks at the fuel pump" and it was recommended that the fuel pump and fuel sender be replaced. Additionally, the leak apparently damaged the electrical wiring harness to the fuel pump and that also needs to be repaired. There were no warning lamps or messages displayed that alerted me to this problem. Obviously, this is a hazard to safety.
The contact owns a 2011 Mercedes-Benz C300. The contact stated after adding more than 3 gallons of fuel to the vehicle, there was a strong fuel odor inside the cabin of the vehicle. The contact stated that the failure had been recurring and was making him unwell. The vehicle was taken to the dealer, where it was diagnosed and determined that the failure was related to NHTSA Campaign Number: 12V557000 (Fuel System, Gasoline). 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 unknown.
I suspect a failure in the fuel tank / system seal, which is allowing gas fumes into the cabin. There is a strong smell of gasoline inside the cabin especially after a full tank refill. This issue was also a problem for my 2008 Mercedes Benz E350. It has not been inspected but since my E350 had a similar extended warranty repair, I assume this would be similar. The strong fumes and odor in the cabin is a health risk of breathing the fumes or explosion. There are no warning lamp to indicate this failure. No recalls or extended warranty currently to fix this problem.
I started to smell gas after filling my tank. Once the gas level went down, the odor disappeared. I took car to dealer who said car needs new gas tank (issue on top of tank) and cost is approx $5K for parts and labor. I started reading about same exact issue on same C300 model and year 2011. I was advised that car with high mileage of 114,000 was not worth repairing even though there are no dents, cosmetically very nice, new tires, always dealer maintained. I have the dealer inspection paperwork
When the fuel tank is full, there is a strong smell of gasoline at the rear of the car. The gasoline odor is extremely strong on the outside, and very strong on the inside. (This is NOT due to overfill or spillage). I searched some Mercedes-Benz blog sites, and discovered others are experiencing similar problems since 2019 to now. The strong gasoline odor can likely pose a health risk. There is also real concern about potential fire or explosion risks.
Related recalls
Fuel system, gasoline
Mercedes-Benz is recalling certain model year 2011-2012 S400, S550, S550 4Matic, S63 AMG, C300, C300 4Matic, E350, GLK350, GLK350 4Matic, CL550 4Matic, and CL63 AMG vehicles manufactured from April 18, 2011, through July 12, 2011.
Remedy: Mercedes-Benz will notify owners, and dealers will replace the fuel filter, free of charge. The recall campaign is expected to begin in February 2013. Owners may contact Mercedes-Benz at 1-800-367-6372.
Fuel System complaints in other C300 years
Frequently asked questions
How common are fuel system problems on the 2011 Mercedes-Benz C300?
NHTSA has 44 complaints about the fuel & propulsion system of the 2011 Mercedes-Benz C300, 9% of the model year's 480 complaints.
Is there a recall for 2011 Mercedes-Benz C300 fuel system problems?
Yes — NHTSA recall 12V-557 (fuel system, gasoline, Dec 3, 2012). Recall repairs are free at authorized dealers.
At what mileage do 2011 Mercedes-Benz C300 fuel system problems start?
Half of the complaints with a recorded mileage happened before about 80,000 miles, and 13% before 25,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.