Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2009 Mercedes-Benz C300 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2009 Mercedes-Benz C300. The contact stated that she had experienced several electrical failures with the vehicle including the power seat and power windows, the parking brake, the exterior lighting, and the air bag warning lights. The contact also stated that the vehicle would lose motive power and stall while driving at various speeds with several unknown warning lights illuminated. The dealer was notified of the failure but offered no assistance. Upon investigation, the contact linked that failure to NHTSA Campaign Number: 22V168000 (Exterior Lighting, Electronic Stability Control, Engine and Engine Cooling). The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 120,000.
The contact owns a 2009 Mercedes-Benz C300. The contact stated while driving approximately 65 MPH, the instrument cluster started flickering and the vehicle stalled. The contact stated that the power steering and brakes were operable. The contact pulled off the highway and shifted the vehicle into park(P). The vehicle failed to restart and was towed to the dealer. The vehicle was not yet diagnosed or repaired. The manufacturer had been informed of the failure. The contact researched online and related the failure to NHTSA Campaign Number: 22V168000 (Exterior Lighting, Electronic Stability Control, Engine and Engine Cooling) however, the VIN was not included. The failure mileage was approximately 119,000.
The contact owns a 2009 Mercedes-Benz C300. The contact stated that while driving at an undisclosed speed, the "SRS System Requires Service" was displayed. The air bag and check engine warning lights were illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the vapor canister shutoff valve but had not provided a diagnosis for the SRS system. The vehicle was repaired. The manufacturer was notified of the failure, and a case was opened. The failure mileage was 99,000.
The contact owns a 2009 Mercedes-Benz C300. The contact stated while driving at an undisclosed speed, she became aware that the coolant level was low. The contact added coolant to the reservoir. The contact stated that the coolant reservoir burst open. The vehicle was towed to an independent mechanic who replaced the coolant and hose. The vehicle was taken to the local dealer but was not diagnosed or repaired. The vehicle was repaired, but the failure recurred. Additionally, the indicator lights became inoperable. The check engine warning light was illuminated. The contact stated the failure was associated with NHTSA Campaign Number: 22V168000 (Exterior Lighting, Electronic Stability Control, Engine and Engine Cooling). The manufacturer was contacted, but no assistance was provided. The failure mileage was unknown.
The contact owns a 2009 Mercedes-Benz C300. The contact stated that the coolant warning light was frequently illuminated due to low coolant. The vehicle was taken to an independent mechanic where the engine hose and other engine parts were replaced. Despite the repair, the coolant light returned soon after the initial repair. The contact then took the vehicle to a dealer where the failure was linked to NHTSA Campaign Number: 22V168000 (Exterior Lighting, Electronic Stability Control, Engine and Engine Cooling); however, the VIN was not included in the recall. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was unknown.
Tl* the contact owns a 2009 Mercedes-Benz C300. While stopped at a red light, the engine revved and the vehicle accelerated. The brake pedal was depressed, but failed and the contact crashed into the rear of another vehicle. The air bags failed to deploy. A police report was filed and there were no injuries the vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 54,000. Updated 02/21/17 updated 9/5/18
Last week took vehicle to get serviced at Mercedes Benz of beverly hills. When I got it back I heard a whistling/flapping noise. Immediately returned to Mercedes service. Was told its nothing of concern if the noise only happens in the mornings and dissipates when driving. Expressed concern about a 1100 mile road trip ahead and wanted to make sure it was safe to drive. Was reassured it was just fine. Upon arriving at my destination the noise escalated non-stop come to find out it was the belt tensioner on my vehicle. The serpentine belt was nearly shredded. The vehicle had about 70,000 miles on it. After doing some quick search online, it seems that this is not an isolated issue, but rather a widespread issue with this vehicle. I'm pissed that the service advisor played stupid as if this was not a known widespread issue and put my safety at risk. …
Common and known issue with m Benz C300 eis/els/steering column. Car engine just dies and will not start due to electrical component malfunction. An expensive, possibly dangerous problem that has not been recognized by Mercedes-Benz it appears from the other comments on this forum and others. My 2009 C300 was running fine. I maintain regular service. Stopped to grab lunch. Fortunately, I was not in motion or in a dangerous area or in the middle of night in the middle of nowhere. The car would not re-start, yet the lights, radio, panel all appeared to be working, although "remove key from ignition" message appeared. Thought it could be a battery or alternator issue. Had to have car towed to 2 different places, the last of which was the mbenz dealership over an hour away. This occurred at 80K miles on odometer. A major safety and possibly dangerous situation. …
I went to class on the date of 11/13/2015 and when I came out the vehicle would not start. After having the vehicle towed to the dealership, I was advised it would be $952.56 for an electrical issue due to no fault of my own and can happen at anytime. So I inquired on how long this would be covered for? I was told its electrical and can happen at anytime, it's like a cellphone or a computer. Yet those have warranties against issues like that whereas something I paid thousands of dollars does not. I have seen many complaints about this online and don't understand why they have not recalled this and continue to rip consumers off. Some even advising this has happen to them on the road which could very well lead to a major accident , it it has not already.
Parked my car overnight and went to start it in the morning and would not start. The key would turn but got no lights on the dash and radio would not work. The steering wheel did not unlock. Tried to jump it but same results. Battery tested fine, checked all the fuses and they were all good. After researching on the internet the steering lock failed. This seems to be a more than frequent issue with this car. This happened out of the blue without any indication that something was going wrong. I'm glad I was home and not hundreds of miles away. Why is there not a recall?
Related recalls
Engine and engine cooling › Engine › Engine control module (ECU/ECM) › Software
Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2010 E350, 2014 G550, 2008-2009 C300, 2008 C350, 2009 CLK550, 2007 SL550, SLK280, and 2008 SLK350 vehicles. Various control units may have been updated with incorrect software configuration during a service repair.
Remedy: Dealers will update the software configuration on the affected control units, free of charge. Owner notification letters were mailed May 3, 2022. Owners may contact MBUSA customer service at 1-800-367-6372.
Engine complaints in other C300 years
Frequently asked questions
How common are engine problems on the 2009 Mercedes-Benz C300?
NHTSA has 22 complaints about the engine & cooling of the 2009 Mercedes-Benz C300, 4% of the model year's 576 complaints. The component named most often is exhaust system (1 mentions).
Is there a recall for 2009 Mercedes-Benz C300 engine problems?
Yes — NHTSA recall 22V-168 (software, Mar 18, 2022). Recall repairs are free at authorized dealers.
At what mileage do 2009 Mercedes-Benz C300 engine problems start?
Half of the complaints with a recorded mileage happened before about 76,000 miles, and 5% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 0 fires and 0 injuries to engine & cooling 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.