2015 Mercedes Benz C300 other reported problems

UNKNOWN OR OTHER

Failed/Malfunctioned Component: Rear subframe (structural/chassis component) exhibited advanced corrosion (perforation/rust-through), compromising structural integrity and alignment/handling. Availability for Inspection: Yes. The vehicle and the subframe are available for inspection upon request. I can provide photos, videos, and repair estimates if needed. The corroded subframe is fracture and detach suspension mounting points, which may lead to: Sudden loss of vehicle stability or control (especially during braking, cornering, or over bumps). Unpredictable alignment changes causing pulling, vibration, or abnormal tire wear that can escalate into a loss-of-control event. Increased stopping distance and potential for wheel misalignment or collapse, raising the risk of a crash involving occupants and other road users. I limited driving/use due to the risk; issue is a structural safety concern rather than cosmetic. Confirmation: Yes on multiple visits since Oct 2023 -Yes—diagnosed and documented by Mercedes-Benz of Silver Spring on Oct 2 2023, Nov 2023 and Dec 2025. Technician confirmed severe corrosion/rust perforation on the rear subframe requiring replacement. No No

NHTSA complaint #11712059 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Rear subframe rusted out, car is not safe to drive

NHTSA complaint #11698179 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

I took my 2015 vehicle to the Mercedes dealership and learned the rear subframe is rusted and has holes on two sides. I was warned that it is a safety hazard and could lead to a lack of control and other dangerous situations. I also learned that other 2010 through 2014 Mercedes models in the same class have been recalled for this exact concern. I am disappointed and upset to learn that those concerns are known, but not addressed in this model and put customers at risk.

NHTSA complaint #11687651 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Rear-subframe corrosion at the lower-control-arm mounts has progressed to the point where both arms have play and produce loud metallic bangs while braking or turning at low speed. Two independent shops lifted the car, documented flaking rust around the bushing sleeves, and advised the subframe is structurally compromised and could let a control arm detach under load. The corroded subframe remains installed and can be inspected on request. Safety risk: a detached rear control arm would cause sudden, unpredictable steering and loss of control. The vehicle already pulls right under braking, and feels very unstable in curves Problem has been reproduced and photographed by two independent repair facilities. No manufacturer representative has inspected the vehicle so far. Additional component failures possibly linked to the same progressive chassis stress: premature wear of both front CV axles; timing-chain stretch with worn guides; slack oil-pump chain; upper & lower oil-pan gasket leaks; water-pump seepage; right engine-mount collapse; persistent misfire traced to a loose intake-hose clamp; transmission-cooler hose clip released under pressure, dumping all ATF and destroying the automatic transmission; excessive play in all four lower control-arm bushings. The transmission and the other components were replaced 1-2 months before the subframe bro History: A faint clank from the rear suspension first appeared roughly three years into ownership. Dealer service dismissed it as “normal noise,” and warranty would not cover “loud clanks,” so the issue went unaddressed. The noise has grown steadily into the current condition, suggesting long-term subframe corrosion that was never inspected or remediated. No collision, flood, or off-road use; the car has typical Northeast winter-salt exposure. The failure pattern matches subframe-corrosion cases already acknowledged by the manufacturer on this model, although this serial number is not yet included in the official campaign.

NHTSA complaint #11663816 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Structure,Body.Roof & Pillars

NHTSA complaint #11663519 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Sunshade on panoramic sunroof broke off and tore sunshade. Took it to MB service center and was told it is known issue for that model and many more with some part snapping off causing the damage and cost to repair is between 2500-3000. Have been reading online and lot of people seem to have same issue with the panoramic sunroof and shade not syncing together. Seems to be concern manufacturer should be looking at if there’s numerous vehicle with same issues. Part snapped off when trying to open up sunroof on hot summer day

NHTSA complaint #11654223 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Engine Light- Crankcase Ventilation Valve Replacement P052E71. Vehicle will jolt aggressively at the time of acceleration.

NHTSA complaint #11653609 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Have noticed a lot of air noise coming from the panoramic sunroof of my vehicle when driving, and now have issues of it opening or closing properly. I researched and found a recall regarding the issues my vehicle is having, and brought it into a dealership for diagnosis. Was told my vehicle VIN was not included in the recall. This is a dangerous issue that needs to be remedied. If the sunroof malfunctions I’m afraid it will come loose from the vehicle as it is doing the same things that the recalled VIN vehicles had issue with. Mercedes needs to update and add additional VINs to this recall. I did not repair, as I was told the entire thing will need to be replaced.

NHTSA complaint #11652756 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Panoramic roof explode sound like a gunshot but the roof exploded

NHTSA complaint #11647581 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Check engine light came on, it has to be with the Positive Crankcase Ventilation Valve. So I found out that other people are experiencing the same thing. So I know that there is a recall by the manufacturer. And I want to do the same for me.

NHTSA complaint #11641447 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Crank case ventilation Valve needs replaced. This is a hazard and multiple Mercedes owners have reported the same issues.

NHTSA complaint #11640652 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

The rear subframe rusted and needed complete replacement. The service department would not pass the car for inspection without replacement. My brother, who also has a Mercedes C300 model but from the prior year, reported that he had the exact same issue. However, Mercedes issued an extended warranty on his model. In researching this issue, I have discovered that this rusted subframe issue is prevalent in C300 models in all years, not just the model years before mine. I compared the service notes from my invoice with my brother's invoice. It is the exact same issue. I contacted both the Mercedes dealership and Mercedes corporate about this issue, seeking resolution. I provided them with all the documentation. Their answer is simply that my VIN does not qualify under their extended warranty and refused to look into it further, despite my pointing out that it is the exact same problem.

NHTSA complaint #11612294 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Crankcase ventilation valve. PCV valve has failed causing check engine light. Very common issue on this model according to my research. The dealer does not have this product in stock to facilitate a repair and no support to find the part. Very difficult when trying to pass an emissions test and this is the last thing holding that back.

NHTSA complaint #11595223 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

My car is a 2015 Mercedes Benz, I bought it at the agency in 2022. When I tested the vehicle at the agency, I noticed the steering was a little hard. I asked the sales person and he told me it was normal. Then, after 1 year and 5 months, it was on its way. I went to work and the steering wheel jammed and it wouldn't cross and the car turned off then it didn't want to start and it said the following on the dashboard power stering see operator manual

NHTSA complaint #11583449 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

I got an oil change since it was due then “P052E” It’s a very common issues with the engine first time it’s happened at 66K miles.

NHTSA complaint #11582276 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Positive crankcase ventilation regulator valve failing and code P052E comes up. Mercedes Benz said this is a problem with all 2015 c300 and should be recalled

NHTSA complaint #11580362 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Crankcase breather faulty

NHTSA complaint #11570674 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

The panoramic sunroof is faulty. Doing a simple search online showed that this is a common problem amongst my vehicle model where parts are loose or misinstalled and it is a safety concern in a potential accident or rollover. My dealer is now looking into it and it is also an excessive out-of-pocket cost to make the vehicle safer. Something I do not expect from a high-end vehicle manufacturer. I identified this due to the rattling sound in the ceiling/sunroof.

NHTSA complaint #11570417 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Front drive shaft on 2015 Mercedes Benz C-300 severed from u-joint(s) on highway, causing catastrophic failure of components and significant damage to front exhaust, catalytic converter, and heat shields. Damaged observed on transmission and/or engine block. The approximate cost to repair was $6,500.00 in parts and labor. Failure of subject component(s) resulted in loss of some control and acceleration. Prior to failure, observed increasing vibration from center of vehicle while exceeding 65 mph but no more than 80 on highway. Audible clunking noise when shifting from "park" or "neutral" to "drive." No warning lamps and/or messages regarding failed component(s). Vehicle has not been inspected by manufacturer, police, and/or insurance representatives. Dealer provided inspection and findings.

NHTSA complaint #11563176 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

P052E. Positive crankcase ventilator valve replacement.

NHTSA complaint #11547209 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

After getting gas my check engine came on steady. Stayed on until cleared. After getting gas a 2nd time check engine light came on again, stayed on, but went out. Then after getting gas a 3rd time, check engine light came on again. Checked by a local Mercedes shop, code showed intake line oil separator bad. Owned this car for 7 years, never had an issue like this. 50,516 miles currently. Quote for repair is high, over $1000 dollars. All episodes of check engine light have occurred in a 4 week time frame.

NHTSA complaint #11545905 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

2015 made C399 PVC change cost more than $1,000. Almost every driver has this issue.

NHTSA complaint #11541265 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

My 2015 Mercedes c300 only has 39k miles and suddenly the engine light on, when I check, the dealer it shows that I need Positive Crankcase ventilation valve replace. it cost $2300. This is basically a brand new car and needing this repair every 30k is a joke please issue a recall and have Mercedes held responsible

NHTSA complaint #11528389 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

FRONT STATIONERY PANEL FAIL OFF WHOLE DRIVING I SEE IT IS IN RECALL BUT DO NOT SEE MY VIN HOW CAN I GET THIS FIXED PER RECALL

NHTSA complaint #11518471 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Hi i have seen lot of customers have filed this cause happening in all 2015 to.2018 c300 its crank case vent valve needs to be changed every 30 to 60k miles lt of posts i have seen i just want mercedes to recall this problem.as its $2400 to fix this because something they didnt did right and part goes bad . Pls help.us reach this so they can do recalls why we have to pay 2400

NHTSA complaint #11502701 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

I took my vehicle to the dealership to have recall worked on (top sunroof panel) apparently they refused to work on it because my sunroof is not working. I received a letter after i financed the vehicle stating that there was a recall so to take it in to the dealership and if sunroof needed to be fixed it would. Long story short, back in July the panel detached from my vehicle while i was on the freeway. Thankfully I didn’t cause an accident but I would like some help so the dealership can fix the recall.

NHTSA complaint #11479093 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

Crankcase ventilation (PCV system), on C300 and GLC 300 is a know issue with this model care fro 2015 to 2021, yet Mercedes Benz manufacture the cars the same way with addressing in order to over charge customers and claim it’s a wear and tear part

NHTSA complaint #11477283 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

This is in regard to my 2015 Mercedes Benz C300 4 matic. I was driving at the normal speed of approximately 65mph on the highway. When out of nowhere, I heard a very loud wind noise. I was terrified since I was alone and was not sure why or what happened. I pulled over and noticed the front panel of my Sunroof glass was missing. I was very disappointed as I have always believed that MB has had a strong reputation for their cars. I circled back around and was able to find the part on the side of the highway, but it was broken. I have had heavy-duty tape covering the space so water cannot get in. I contacted my local MB repair shop and told me the part would be $1100 and labor would be additional.

NHTSA complaint #11475572 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

PCV valve

NHTSA complaint #11473344 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

The crankcase ventilation valve has gone out on my car. This is a continual problem with these vehicles at low mileage. Mercedes Benz should recall the part for repair as they stated it could damage the engine.

NHTSA complaint #11460195 — an unverified report by a vehicle owner.