AI Damage2018 Mercedes-Benz C 300 4matic: common problems
Owners of the 2018 Mercedes-Benz C 300 4matic filed 12 complaints with NHTSA, most often about structure and engine. The maker issued 127 service bulletins for this year. Details by component below, with sources.
Key figures
- Owner complaints
- 12
- Technical service bulletins (TSB)
- 127
What fails most often
- 1 Structure 33% of all complaints
- 2 Engine 17% of all complaints
- 3 Electrical system 8% of all complaints
- 4 Visibility 8% of all complaints
- 5 Steering 8% of all complaints
- 6 Suspension 8% of all complaints
- 7 Air bags 8% of all complaints
- 8 Communication 8% of all complaints
- Structure: 4 complaints (33% of all); manufacturer bulletins for this component: 9.
- Engine: 2 complaints (17% of all); manufacturer bulletins for this component: 9.
- Electrical system: 1 complaints (8% of all); manufacturer bulletins for this component: 38.
- Visibility: 1 complaints (8% of all); manufacturer bulletins for this component: 9.
- Steering: 1 complaints (8% of all); manufacturer bulletins for this component: 5.
Symptoms owners describe
How many of the 12 NHTSA complaints mention each symptom (automatic count from complaint text; one complaint can mention several).
Components owners complain about
| Component | Owner complaints | involving a crash | Technical service bulletins (TSB) |
|---|---|---|---|
| Structure | 4 | 0 | 9 |
| Engine | 2 | 0 | 9 |
| Electrical system | 1 | 0 | 38 |
| Visibility | 1 | 0 | 9 |
| Steering | 1 | 0 | 5 |
| Suspension | 1 | 0 | 2 |
| Air bags | 1 | 0 | 0 |
| Communication | 1 | 0 | 0 |
| Seat belts | 1 | 0 | 0 |
| Powertrain | 0 | 0 | 27 |
| Exterior lighting | 0 | 0 | 14 |
| Equipment | 0 | 0 | 12 |
| Engine and cooling | 0 | 0 | 7 |
| Fuel/propulsion system | 0 | 0 | 5 |
What owners report
Short excerpts of NHTSA complaints in the original wording. These are owner statements not verified by NHTSA; personal data removed.
2018 Mercedes C300 - a hole rusted through the rear subframe causing structural safety concerns. This car has been routinely washed weekly and the frame should not have rusted through within only 8 years. This also led to a large repair bill.
This has caused my sunroof to malfunction, and it won't close now. I garage my car and barely drive it. I bought it used in Dec. 2021. There was about 46,000 on it in Dec 2021 and now (June 2026) the mileage is 51,000. Yes, the car is available for inspection. 2) I was on the freeway, didn't see it come off.
the front roof panel located between the windshield and the panoramic sunroof may not have been bonded correctly to the vehicle during a prior repair, allowing the front panel to detach from the vehicle., Consequence A detached roof panel can become a roao hazard, increasing the risk of a crash I went to the…
The contact stated that the front passenger's and driver's side seat belts had failed to retract and return to the stowed position. The contact related the failure to NHTSA Campaign Number: 21V032000 (Seat Belts); however, the VIN was not included.
One day went to drive and the vehicle wouldn't turn and an error message popped up "power steering malfunction, check owners manual" Had it towed to dealer and they said they couldn't find anything wrong with it. According to the dealer, no sign of wear and tear, no physical damage,
Very common problem on all Mercedes - code P052E - second time on this car. Engine light, 2nd time on this car. Car is 2018 and has 45k miles. First time it was at 28037 miles. This is a MAJOR issue costing consumers $1500-$2500 to repair and needs a recall from manufacturer
P052E check engine code. Positive Crankcase Ventilation failed with less than 28K miles. Common reported problem but not covered after warranty period, even with extended warranty addition. It's a major part of the engine function and 6 hours of labor to replace.
The rear windows failed to raise and lower as needed. The contact took the vehicle to the dealer to be repaired. The exact repairs were unknown. The approximate failure mileage was 49,000.
When owners complained
NHTSA complaints by filing year. The peak shows at what age the problems show up most.
Comparison
By complaint count this model year ranks 10,162 of 36,659 model years in the NHTSA data (top 28% most complained about).
On average one model year of the C 300 4matic has 2 complaints (8 years in the data). This year has 12, above average.
What to check before buying
- Structure. Rails, pillars, panel gaps, signs of pulling or welding.
- Engine. Cold start, unusual noises, oil leaks and engine codes.
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
- Visibility. Wipers, mirrors, defrosters, cracked glass.
Manufacturer service bulletins
Bulletin titles as filed with NHTSA.
- Complaint Clanking noise from the area of the speakers in the doors
Cause Under analysis. Remedy To narrow down the cause, first of all remove the door trim. • If the noise continues to occur even with the door trim removed, then continue the diagnosis working towards the speaker and…
- Complaint Slight creaking noises when steering
Cause Noises may come from one or more sleeves of the horn contact plate. Remedy Remove the horn contact plate and check the sleeves for noise; see attached video. If necessary, apply lubricant to the sleeves.
- Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic /9G‑TRONIC automatic…
Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic /9G‑TRONIC automatic transmission) and 725.1 (NAG3 facelift/9G‑TRONIC automatic transmission facelift) For faster, more effective and…
- Complaint Repeat workshop visit for vehicle vibration while braking from 60MPH. NOTE
Although the symptom is similar to a tire or wheel vibration, it is usually readily noticeable that it is distinctly different if it happens at all times or only while braking. Cause Although the cause of the vibration…
- Complaint Only vehicles with a variable transfer case are affected
This can be identified through control unit N45 or N15/7 in the quick test. When accelerating with light load, vibrations or jolting sensation may come from the drivetrain. It may be mistaken for a harsh shift. Cause…
- Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic / 9G‑TRONIC automatic…
Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic / 9G‑TRONIC automatic transmission) and 725.1 (NAG3 facelift/9G‑TRONIC automatic transmission facelift) For faster, more effective…
- Complaint During part of the steering movement, it feels heavier or more difficult to steer in the same…
Complaint During part of the steering movement, it feels heavier or more difficult to steer in the same spot every time. OR Rattling, humming, dry sliding/gravel noise from the electric steering system when steering…
- Dear Mercedes-Benz Owner
In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfaction of our customers, Mercedes-Benz USA is extending the warranty coverage for the Diagnostic Module for…
- Complaint Tailgate opens unintentionally
Cause Accidental or unnoticed activation of the button to open the tailgate on the vehicle key. EXAMPLE: when stored in trouser pocket, handbag etc. Remedy As of the 6th generation, the vehicle key can be recoded so…
- Complaint A popup is seen on the HU with the message "data connection temporarily not available"
Potentially affected functionalities in NTG4.5, NTG5 1.Weather 2.Local Search 3.IP Radio 4.Send2Car 5.Speech Detection Service 6.Navigation 7.iHeartRadio 8.Traffic Cams Cause MB Apps is sundowned for all vehicles with…
- Complaint 1
General Diagnostic Tips 2. One or More PARK Sensor Activations 3. Red Ring Around Vehicle 4. "Active Parking and Parking Assist Inoperative" on Instrument Cluster 5. Cameras 6. Other Park Topics. Cause Various root…
- Complaint This document is intended as a pre-case diagnostic reference for transmission related concerns
It will also ensure that if a case is necessary, all supporting documentation is available. This should not be used on its own as justification for creating a TIPS case. Cause The root cause will vary depending on the…
NHTSA lists 127 bulletins for this year; the 12 newest are shown here.
Other years of this model
Questions and answers
What are the most common problems with the 2018 Mercedes-Benz C 300 4matic?
Owner complaints to NHTSA most often mention: structure, engine, electrical system. Total complaints: 12. The most frequent symptoms in complaint texts: windows, sunroof (33%), warning lights, check engine (25%), rust, corrosion (8%).
How many service bulletins (TSB) were issued for the 2018 Mercedes-Benz C 300 4matic?
NHTSA lists 127 manufacturer service bulletins for this year. A bulletin tells dealers how to diagnose or fix a known issue; it is not a recall.
Should I buy a 2018 Mercedes-Benz C 300 4matic from a US auction?
Owner complaints describe defects, not crash damage. Before bidding, check the components listed above and review the lot photos: VinWind builds a report of visible and hidden damage by VIN.
Other 2018 models
Read also
Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-06.