Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2017 Mercedes-Benz C300 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2017 Mercedes-Benz C300. While driving at approximately 15 mph, the contact observed smoke emanating from under the hood. The vehicle was driven to her work location and parked. Upon exiting the vehicle and opening the hood, she observed orange flames coming from the engine compartment. A parking attendant extinguished the fire, and a police and/or fire report was filed. The vehicle was towed to a dealer and diagnosed with a fuel line leak that caused the engine harness to come apart. The leaking fuel hose from the high-pressure fuel pump caused damage to the high-pressure pump, engine harness, vacuum transducer, and coolant feed line from the thermostat to the firewall. The following components needed replacement: high-pressure fuel pump, rubber fuel hose, engine harness, pressure transducer, and intake manifold. The vehicle was repaired. …
The contact owns a 2017 Mercedes-Benz C300. The contact stated while driving at an undisclosed speed, the check engine warning light was illuminated but then disappeared. The vehicle was taken to an independent mechanic to be diagnosed. The vehicle was diagnosed with a failed actuator. The contact was informed that an actuator needed to be replaced. The vehicle was not repaired. The contact was informed of NHTSA Campaign Number: 21V961000 (Fuel System, Gasoline) however, the VIN was not associated with the recall. The manufacturer was made aware of the failure and advised the contact to report the failure to the NHTSA Hotline. The failure mileage was approximately 100,000.
MB USA extended the warranty coverage on the low pressure fuel hoses that connects to the high pressure fuel pump. The reason is "under certain cold ambient conditions during a cold start of the engine, the low pressure fuel hose at that connection may experience slight fuel weeping". MB USA, however, ruled out a safety risk. NHTSA needs to investigate it. If MB USA found the fuel pressure line is defective, they needed to do a recall. I believe it must be a recall as fuel leaks is not only a safety risk but also a serious health hazard to the occupants. What if the occupants have sinusitis and don't smell well. What if the leaks is too small to smell enough but can still be a health issue.
Diagnosis code P052E PCV regulator valve replacement/crankcase replacement. Dealership does not want to acknowledge code while car was under warranty despite proof that it existed when check engine was diagnosed. Now code keeps coming back with check engine light on dashboard. To replace part, the engine has to be taken down since the crankcase is inside the engine. This is a malfunction during assembly/manufacturing, it is impossible to damage part while under usage. Mercedes Benz should be held responsible for part replacement and labor. I urge you to investigate this matter with other clients and ask the manufacturer to replace part and pay for labor.
At approximately 26,500 miles of use, the check engine light came on in my Mercedes Benz C300. I brought the vehicle to the dealership and they informed me that the diagnosis was a crankcase vent valve malfunction. The MB fault code is P52E71. After paying Mercedes to fix the issue, I found forums on the internet where many other MB owners reported the same issue at around the same mileage. Being that this seems to be a common malfunction with the C300, I believe that it should be considered as a recall issue. I don't know what could have happened if I didn't service the vehicle, but any engine issue is dangerous while a vehicle is in motion.
I have a mercedes c300 2017 and recently I was driving my car and the check engine light came on all of a sudden so I took it to my local shop to diagnose it they told me it was the PCV valve, so I called mercedes and they're telling me that this is not covered and of course my warranty is no longer covered I have about 63k miles on the car. Mercedes is saying they don't have a recall for this but I've googled around and multiple people are saying the same issue happened to them around the 55-65k range. It's super frustrating that this doesn't flag a recall.
Please see attached letter: [redacted] Mercedes Benz Crankcase Valve Claim.pdf, repair estimate and other correspondence from Mercedes-Benz. This is an well-known issue where there is a gas lead from the engine where Mercedes insists doesn't pose a safety issue. During cold starts there is a smell of gas in the cabin and this is prevalent in colder climates like New England. Mercedes should make cars for all markets that are safe.
Keep getting a code P052E! Changed the oil and code went away for a few days then came back. Looked into getting it fixed and it seems like Mercedes has known about this issue and hasn't called for a recall on this piece of equipment! Very costly to fix and says it needs to be replaced every 30k to 50k miles! At around 1k to 3k to fix everytime that's something they should recall
My preowned vehicle has a strong gas odor in the cabin while operating. I don't see any safety recalls but I did read online that a class action lawsuit proved my model may have faulty fuel parts causing seepage and the watranty is extended to 10yr/120k miles. I have scheduled maintenance this week but would like to be certain the warranty will cover this. Thank you.
There is a short rubber fuel line/hose in the engine compartment that is attached with compression clamps; the hose connects the fuel line from the gas tank to the high pressure fuel pump. When it gets cold outside (below ~40 degrees Fahrenheit) the clamps loosen a bit and the hose will leak gas The entire interior smells like gasoline, really bad.
Fuel System complaints in other C300 years
Frequently asked questions
How common are fuel system problems on the 2017 Mercedes-Benz C300?
NHTSA has 33 complaints about the fuel & propulsion system of the 2017 Mercedes-Benz C300, 15% of the model year's 216 complaints.
Is there a recall for 2017 Mercedes-Benz C300 fuel system problems?
No. NHTSA lists no fuel & propulsion system recall for the 2017 Mercedes-Benz C300, though it has 15 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2017 Mercedes-Benz C300 fuel system problems start?
Half of the complaints with a recorded mileage happened before about 55,000 miles, and 17% before 25,000 miles.
Is it dangerous?
Owners linked 0 crashes, 1 fire and 0 injuries to fuel & propulsion system problems on this model year. If you notice symptoms, have the car checked before driving further.
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.