AI Damage2018 Mercedes-Benz S 450: common problems
Owners of the 2018 Mercedes-Benz S 450 filed 7 complaints with NHTSA, most often about service brakes and forward collision avoidance. The maker issued 116 service bulletins for this year. Details by component below, with sources.
Key figures
- Owner complaints
- 7
- Technical service bulletins (TSB)
- 116
What fails most often
- 1 Service brakes 29% of all complaints
- 2 Forward collision avoidance 29% of all complaints
- 3 Powertrain 14% of all complaints
- 4 Steering 14% of all complaints
- 5 Seat belts 14% of all complaints
- Service brakes: 2 complaints (29% of all); manufacturer bulletins for this component: 1.
- Forward collision avoidance: 2 complaints (29% of all).
- Powertrain: 1 complaints (14% of all); manufacturer bulletins for this component: 31.
- Steering: 1 complaints (14% of all); manufacturer bulletins for this component: 2.
- Seat belts: 1 complaints (14% of all).
Symptoms owners describe
How many of the 7 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) |
|---|---|---|---|
| Service brakes | 2 | 0 | 1 |
| Forward collision avoidance | 2 | 0 | 0 |
| Powertrain | 1 | 0 | 31 |
| Steering | 1 | 0 | 2 |
| Seat belts | 1 | 0 | 0 |
| Electrical system | 0 | 0 | 37 |
| Exterior lighting | 0 | 0 | 15 |
| Equipment | 0 | 0 | 7 |
| Structure | 0 | 0 | 7 |
| Suspension | 0 | 0 | 7 |
| Visibility | 0 | 0 | 7 |
| Engine | 0 | 0 | 5 |
| Fuel/propulsion system | 0 | 0 | 5 |
| Engine and cooling | 0 | 0 | 2 |
What owners report
Short excerpts of NHTSA complaints in the original wording. These are owner statements not verified by NHTSA; personal data removed.
Additionally, the check engine warning light was later illuminated. The vehicle was taken to the dealer where it was diagnosed with transmission valve body failure. The contact was informed that the transmission valve body needed to be replaced. The vehicle was not repaired.
Steering wheel became extremely stiff to turn and a message that read âsteering malfunction increase physical effortâ appeared while driving at around 30 mph while in a vacation trip, not only was this extremely unsettling since it happened suddenly but I had to act fast to avoid a collision with other vehicles,…
The contact stated that the brakes failed to work as needed. The contact stated that the âService Requiredâ message was displayed on the instrument panel. The vehicle was taken to a dealer and was diagnosed with electronic parking brake failure. The manufacture was not notified of the failure.
Iâm reporting this safety concern and seeking advisement from those more knowledgeable than myself on this issue. Recently, as I attempted to actuate the brake of my vehicle.
Tl* the contact owns a 2018 mercedes-benz s450. While driving 75 mph with the cruise control engaged, the automatic braking activated on its own in traffic. The contact had to depress the brake pedal to disengage the cruise control in order to drive safely.
The pre-collision safety feature goes off when there is no collision imminent. It is frightening and could actually cause an accident.
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 12,539 of 36,659 model years in the NHTSA data (top 34% most complained about).
On average one model year of the S 450 has 5 complaints (3 years in the data). This year has 7, above average.
What to check before buying
- Service brakes. Pedal feel, ABS operation, leaks, discs and hoses.
- Forward collision avoidance. Radar and camera: calibration after bumper or windshield replacement.
- Powertrain. Shift quality under load, harsh shifts, transmission codes, CV joints.
- Steering. Steering play, power assist, rack and tie rods after a wheel impact.
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 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 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…
- Complaint Mercedes-Benz USA is currently experiencing limited availability of transmission fluid…
Complaint Mercedes-Benz USA is currently experiencing limited availability of transmission fluid specification ATF 236.17 due to a global supply constraint. 236.17 ATF 1L and 5L (PNs: A002989060312 and A002989060313)…
- This NCU replaces the prior NCU issued on May 15, 2025, and contains additional MY 2023 and MY 2024…
This NCU replaces the prior NCU issued on May 15, 2025, and contains additional MY 2023 and MY 2024 vehicles which are highlighted below. In our continuing efforts to ensure the proper performance of Mercedes-Benz…
NHTSA lists 116 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 S 450?
Owner complaints to NHTSA most often mention: service brakes, forward collision avoidance, powertrain. Total complaints: 7. The most frequent symptoms in complaint texts: brake failure (14%), rollaway, parking brake (14%), warning lights, check engine (14%).
How many service bulletins (TSB) were issued for the 2018 Mercedes-Benz S 450?
NHTSA lists 116 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 S 450 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.