general problems of the 2015 Mercedes Benz C300 - part 1

Rear subframe rusted out, car is not safe to drive.

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.

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 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.

Failed component: front sunroof clip what component or system failed or malfunctioned, and is it available for inspection upon request? sunroof clip, yes. How was your safety or the safety of others put at risk? the glass pane lifted while the car was in motion and had to be held down to secure it until the car stopped. Has the problem been reproduced or confirmed by a dealer or independent service center? yes has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? no were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? no while merging to enter the freeway at approx 45-50 mph I opened my sunroof. At about halfway back the glass began to lift up off the track/railing as if it was going to fly off the track. Had I not been holding the button to open the sunroof I would not have noticed and the entire glass pane would have blown off, possibly damaging the car or worse flying off and hit another car. I had to hold the glass in place to keep it from flying off until I was able to exit the freeway. Once I stopped the car to inspect the sun roof I noticed the clip that secures the glass to the track was broken (crumbled) in the sunroof track. I removed the pieces of broken plastic from the track and was then able to close the sunroof. I am now unable to safely open my sunroof while the vehicle is in motion.

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.

Structure,body. Roof & pillars.

Engine light- crankcase ventilation valve replacement p052e71. Vehicle will jolt aggressively at the time of acceleration.

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.

Panoramic roof explode sound like a gunshot but the roof exploded.

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

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.

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.

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.

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.

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.

Crankcase breather faulty.

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.

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.

P052e. Positive crankcase ventilator valve replacement.

2015 made c399 pvc change cost more than $1,000. Almost every driver has this issue.

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.

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.

Front stationery panel fail off whole driving I see it is in recall but do not see my VIN how can I get this fuxed per recall.

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.

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.

Pcv valve.

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.

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.

I keep getting a litany of warnings on the dash.

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.

The car have anew recall recall #2021070010. The dealership garage isla verde won’t provide me any type of services to my car. Neither repair this safety recall. They cancelled my appointments because I’m not welcome to the dealership.

On 7/17/21 the piece of the top of the car right from the from window leading to sunroof came undone and flew off while on highway. Vehicle was repaired a month later at body shop. This was out of pocket due to not wanting to claim on my insurance due to deductible. This piece flew off at a high velocity with no warning and couldve caused a accident. There was no indication of any issues no lights no warnings signs. There was a loud noise like a brick or large object falling on top which then I heard a lot of air. Recently again in October 5 I was driving on the highway and debree hit my sun roof, my window was shaking and I went to the bodyshop. In the brief drive there some 10 miles the same plastic part repaired was lifted and coming off. On this occasion I used my insurance.

On July the 8th I was driver on interstate highway 65south in birmingham alabama in my 2015 mercedes c 300 when there was a loud thump which startled me and almost caused an accident what happened is the roof panel between the windshield and sunroof flew off it caused damage to my vehicle and almost an accident now when I contacted mercedes they say that it is a recall out for this problem but they do not have a time as to when this can be fixed this will be a problem because now I am not able to drive my vehicle because there is a gape between the windshield and the roof where water and anything else will get into the vehicle this is terrible now I am without a car for who knows how long.

Recall 2021070010----NHTSA #21v197--panoramic roof not boned correctly to the vehicle during prior replacement -.

My daughter was driving at freeway speeds, when she heard, what we now know, is a portion of the sunroof panel flapping and break off. There was no warning, no instrument indication, and assume the broken part was a safety hazard to vehicles following. We took her vehicle to fletcher jones mercedes in newport beach, but they're hesitating about repairing or reimbursing costs, due to the pending nature of the NHTSA recall #21v197.