Mercedes-Benz C300 loss of power problems

Filed Oct 30, 2026 · Engine · NY

I am reporting a potentially serious safety problem involving sudden loss of engine power and an unresponsive accelerator. On August 30, 2026, while I was driving on the highway with my child in the vehicle, the engine suddenly stopped producing power. Pressing the accelerator did not restore normal acceleration. The vehicle was in motion, and the loss of power created a serious safety risk. I believe this happened on two occasions, although I do not have the date and mileage for the other occurrence available. The confirmed incident occurred at approximately 38,198 miles. I brought the vehicle to a Mercedes-Benz dealership. The dealership told me the problem was caused by a software defect and that a software update was needed. The update was performed, and I paid for the repair. I am concerned that the vehicle could unexpectedly lose power again while in traffic, putting occupants and other road users at risk. I am asking the federal safety agency to review this report and assess whether this may indicate a safety-related defect affecting this vehicle or others.

Filed Sep 15, 2026 · Electrical, Engine · CA

The vehicle experienced a severe safety issue involving a sudden loss of motive power in active traffic. 1. Initial Symptoms & Diagnosis: Recently, the Check Engine Light illuminated. Although the light turned off before my scheduled appointment, I still brought the vehicle to an authorized Mercedes-Benz dealership for a safety inspection. 2. Dealer Confirmation: The dealership inspected the vehicle and diagnosed an internal electrical fault with the engine oil control valve and harness. They recommended replacing the parts. Because the vehicle seemed to be running fine and the dealer did not warn me that it was unsafe to drive, I drove the vehicle home to consider the repair. 3. Critical Safety Incident: Shortly after bringing the car home, I was stopped at an intersection. When I attempted to accelerate, the vehicle suddenly entered "limp mode." It lost almost all motive power and would only crawl forward at a very low speed. This sudden loss of acceleration in the middle of traffic put me at an immediate risk of a collision. I had to pull over to the side of the road and restart the engine to regain normal function. 4. Prior Symptom: Looking back, I experienced a similar brief loss of power approximately one year ago. However, the vehicle recovered quickly after I restarted the engine, and no warning lights came on, so I was unaware of the severity of the defect at the time. The vehicle has less than 20,000 miles. An internal engine valve failure causing a sudden loss of acceleration on public roads is a major safety defect. The vehicle is currently parked for safety reasons and is available for inspection upon request.

Filed Jul 1, 2026 · Electrical, Engine · FL

Throttle body and accelerator pedal position sensors failed. Component is available for inspection upon request. Independent service center confirmed failure on 1/3/2026 with 6 stored fault codes: P2101, P0122, P0222, P0123, P0223, P2135. Vehicle shuts off while driving without warning at various speeds. Loss of power steering and power brakes occurs when engine stalls, creating immediate risk of crash, injury or death to occupants and other drivers. Manufacturer customer service confirmed in writing 4 times that engine shutting off while driving is a safety issue and that these exact codes match Service Campaign 2022090005. On 1/7/2026, manufacturer denied campaign applies to this vehicle and refused no-charge dealer inspection, demanding customer pay diagnostic fees to confirm defect they already documented. Vehicle has not been inspected by manufacturer or dealer because manufacturer refuses free inspection. Check engine light illuminated prior to stall events. Manufacturer has actual knowledge of safety defect under 49 U.S.C. 30118 and is creating financial barrier to repair of defect covered by their own service campaign. Request the federal safety agency investigation and order manufacturer to repair under Service Campaign 2022090005 at no charge.

Filed May 19, 2026 · Fuel system · 60,000 miles · FL

The contact owns a 2021 Mercedes Benz C. The contact stated that while driving on the highway, the vehicle began to lose power, riding rough. The check engine light illuminated. The vehicle was towed to the dealer where it was diagnosed with a fuel injection failure. The vehicle read diagnostic code P1CEF85. The manufacturer was made aware of the issue. The approximate failure mileage was 60,000.

Filed Apr 24, 2026 · Electrical, Engine · CA

My C300 MBZ, 2016 is experiencing the same symptoms as indicated in a recall, but my vehicle is not included in that recall. Camshaft: GENERAL REPAIR A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice versa. Cams act as a vital component to your automobile's engine. A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part. Camshafts provide power to the cams which are vital for basic engine operation. The cost of fixing this approximately $10,000 per Mercerdes dealer and estimate from Keyes Mercerdes. The Brief: Mercedes-Benz issued a recall for some model cars tied to a faulty drive shaft.T he problem not only can cause vehicles to lose power but may elevate crash risk, according to the National Traffic Safety Administration. Owners of the affected vehicles can take them to their local dealership to receive free repairs, however per MBZ corporate 2016 C300 not included? Mercedes-Benz is recalling 24,092 cars connected to a drive shaft universal joint that may break, resulting in a sudden loss of drive power.

Filed Apr 23, 2026 · Electrical, Engine · NY

Vehicle has ongoing and recurring electrical and engine-related defects that affect safe operation. The primary systems involved are the electrical system, engine ignition system, and powertrain. The vehicle is available for inspection upon request. Prior service records show issues beginning in 2020 involving repeated electronic system failures requiring multiple repairs and component replacements. Since purchasing the vehicle in April 2023, the vehicle has developed more serious failures, including: – September 2024: Check engine light with loss of power and inability to exceed safe driving speeds – October 2024: Engine misfiring due to ignition coil failure requiring replacement of ignition components – September 2025: Additional ignition coil electrical fault (code P0353) The problem has been reproduced and confirmed through dealership service inspections and diagnostic reports. Warning indicators, including the check engine light, appeared prior to failure events. These defects create a safety risk due to potential loss of power, engine failure, and unreliable vehicle operation while driving, which could increase the risk of an accident. The issues have required multiple repairs without permanent resolution and appear to be ongoing and worsening over time.

Filed Feb 17, 2026 · Engine · GA

I am reporting a catastrophic repeat engine failure on my 2020 Mercedes-Benz C300. On October 9, 2025, with 26,589 miles, the vehicle suffered a Cylinder 2 failure (exhaust valves), causing a dangerous loss of power in traffic. I paid $4,100.43 for a $10,000 plus cylinder head replacement at an authorized dealer (Mercedes-Benz of Atlanta South) on November 13, 2025. Following the repair, the vehicle continued to exhibit multiple 'Check Engine Oil Level' warnings. On February 4, 2026—less than 90 days after the major repair—the engine suffered a total catastrophic failure. The dealer now states the entire engine requires replacement. This repeat failure of a critical engine component at low mileage poses an unreasonable risk of stalling or sudden loss of propulsion on high-speed roads. I am aware of the January 2026 Mercedes-Benz warranty extension (NCU 30-P-072328) for this specific M264 engine defect, which confirms a known manufacturing flaw that the current dealership repair process failed to remediate, leaving me in an unsafe vehicle.

Filed Jan 5, 2026 · Acceleration, Electrical · CA

While driving at approximately 65 mph on the I-405 freeway in Irvine, CA during rainy conditions, my 2019 Mercedes-Benz C300 suddenly and completely lost acceleration without warning. At the same moment, a Check Engine Light illuminated on the dash. I was forced to coast across all lanes and stop in the emergency shoulder in a very unsafe area with high-speed traffic passing close by in low visibility rainy conditions. Multiple vehicles nearly struck us, including one that had to emergency brake directly behind my car in the shoulder. I contacted AAA and the vehicle had to be towed because it was not safe or driveable. My girlfriend was also in the car and both of us experienced significant fear and distress during and after the incident. My mechanic retrieved fault code P019185 and stated this is a known software problem with the engine control unit that requires a Mercedes software update and reset of mixture adaptations per a manufacturer LI/service document. This means the manufacturer appears aware of the defect and the required software fix, yet I received no recall notice or safety warning. A sudden total loss of engine power at highway speeds creates an extreme crash risk and life-threatening danger to the driver, passengers, and surrounding traffic. There have been other serious drivability issues with this vehicle in the past (misfires, coolant pipe failure, etc.), but this incident was the most dangerous. I am reporting this because this defect appears safety-related and could easily cause a fatality if it happens to someone else at freeway speeds. Diagnostic Note from official Mercedes-Benz Fletcher Jones of Newport Beach Mechanic: “FAULT CODE P019185, WILL START WITH PERFORMING THE SOFTWARE UPDATE OF ME CONTROL UNIT, RESET THE MIXTURE ADAPTIONS PER LI DOCUMENT AND RECHECK.” Tow Provider: AAA — tow confirmation available if needed.

Filed Dec 22, 2025 · Engine, Fuel system · FL

This vehicle was brought to an authorized Mercedes-Benz dealership for regularly scheduled maintenance. Shortly after this service, the vehicle began experiencing significant issues including difficulty accelerating, engine hesitation while driving, and noticeable shaking at idle. This car has never overheated. The vehicle was returned to the dealership for inspection. The dealership diagnosed a cracked cylinder head and advised that the repair requires replacement of the cylinder head at an estimated cost of approximately $11,000. The failed component is available for inspection and the vehicle is currently at the dealership. The vehicle has approximately 46,000 miles, has been regularly maintained, garaged, and driven under normal conditions. These symptoms created engine performance issues that could result in loss of power or inability to accelerate while driving, creating a potential safety risk, especially in traffic or at highway speeds. I regularly transport my young grandchild in this vehicle. The possibility of sudden engine failure, loss of power, or breakdown while driving raises significant safety concerns for myself and any passengers, particularly a young child. The failure has been confirmed by an authorized Mercedes-Benz service center. During my own research, I discovered there have been recalls involving similar engines for the same model year, as well as multiple owner complaints reporting similar engine or cylinder head failures on this vehicle. I contacted Mercedes-Benz customer care on December 17, 2025, after receiving the dealership diagnosis, and was advised that I would receive a response within 72 hours. As of today, I have not received any response. I attempted to call customer care again, but the phone system would not accept a voicemail and no representative answered. My case number with Mercedes-Benz is 19653254. No prior abuse, misuse, or abnormal driving conditions occurred. The vehicle was properly maintained.

Filed Nov 19, 2025 · Acceleration, Fuel system · GA

1. The vehicle experienced a fuel injector failure, which is part of the engine fuel delivery system. This failure appears connected to an open Fuel System Control Unit Software Update Recall (Campaign 2024080006) that has been open since May 2024 but was not performed on my vehicle, despite the vehicle being serviced at the dealership in January 2025 for other recall-related updates. The failed injector is still available for inspection upon request. 2. The vehicle began exhibiting symptoms of fuel system malfunction while driving, including rough idling, hesitation, and loss of power. A malfunctioning injector can cause the engine to misfire, stall unexpectedly, or run unpredictably, which creates a high-risk situation in traffic. This placed me, my passengers, and other drivers at risk, especially during acceleration or when merging into traffic. 3. Yes. The issue was diagnosed and confirmed by the Mercedes-Benz dealership, which stated that the injector had mechanically failed. The dealership also noted the open recall for the fuel system software update but claimed it was unrelated. I am seeking clarification because the timing and symptoms suggest there may be a connection. 4. The vehicle has been inspected only by the Mercedes-Benz dealership. Mercedes-Benz USA (MBUSA) has been contacted regarding the issue, but my case was closed without resolution and is currently awaiting review for reopening. MBUSA has not yet inspected the vehicle or the failed component directly. 5.Prior to the injector failure, the vehicle displayed engine hesitation, rough idling, and intermittent performance issues. Eventually, a check engine light illuminated. These symptoms began before the manufacturer-installed software update, and the issue appears to have worsened afterward.