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The Mercedes-Benz S-Class W223 S 450 represents the latest in luxury, technology, and performance. As a flagship sedan, it boasts cutting-edge features, advanced driver assistance systems, and a powerful yet efficient mild-hybrid inline-six engine.
However, no car is perfect, and the W223 S 450 is no exception. Despite its engineering excellence, several owners have reported common issues that affect the car’s performance, reliability, and comfort.
In this comprehensive guide, we will explore the most common problems of the Mercedes S-Class W223 S 450, their symptoms, causes, and possible solutions. Whether you already own this luxury sedan or are considering purchasing one, this article will help you understand potential concerns and how to address them.
Mercedes S-Class W223 S 450 Engine and Performance Issues
The Mercedes S 450 W223 features a 3.0L turbocharged inline-six engine with a 48V mild-hybrid EQ Boost system, providing a smooth balance of power and efficiency.
While this powertrain is technologically advanced, it is not immune to mechanical and electronic problems.
Mild-Hybrid System Malfunctions
One of the standout features of the S 450 is its mild-hybrid system, designed to improve fuel efficiency and provide additional power when needed. However, some owners have experienced issues with the 48V electrical system, including battery failures, power surges, and sudden loss of electric assist.
Symptoms of hybrid system malfunctions include:
Dashboard warning messages related to the hybrid system
Reduced performance or hesitation when accelerating
Difficulty starting the vehicle
A faulty auxiliary battery, software glitches, or problems with the electric motor could be the root cause. If you experience these issues, having the system diagnosed by a Mercedes specialist is essential. In some cases, a software update or battery replacement may resolve the problem.
Turbocharger Lag and Boost Pressure Issues
Turbocharged engines rely on forced induction to deliver power efficiently. Some W223 S 450 owners have reported turbo lag or inconsistent boost pressure, leading to sluggish acceleration and delayed throttle response.
This problem is often caused by:
A faulty turbo actuator
Carbon buildup in the turbo system
Issues with the boost pressure sensor
Routine maintenance, including regular oil changes with high-quality synthetic oil, can help prolong turbo life. If you notice a significant drop in power, it’s best to have the turbo system inspected to avoid potential failures.
Engine Oil Consumption and Leaks
Excessive oil consumption has been noted in some S 450 models. While modern engines use a small amount of oil between service intervals, excessive consumption could indicate problems such as:
Worn valve seals
Piston ring issues
Oil cooler leaks
Symptoms include low oil warnings on the dashboard, visible oil leaks under the car, and increased exhaust smoke. If left untreated, low oil levels can lead to premature engine wear.
Regular oil level checks and addressing leaks promptly can prevent costly engine damage.
Mercedes S-Class W223 S 450 Transmission and Drivetrain Issues
The S 450 is equipped with a 9-speed automatic transmission (9G-Tronic) that delivers smooth and precise gear changes. However, some owners have reported transmission-related issues that affect the driving experience.
Harsh or Delayed Shifting
One of the most frequently reported problems is rough or delayed gear shifting. Drivers have noticed abrupt gear changes, hesitation during acceleration, or jerky downshifts.
The most common causes include:
Dirty or degraded transmission fluid
Software calibration issues in the transmission control unit
Mechanical wear in the valve body
Mercedes-Benz recommends changing the transmission fluid every 60,000 km to maintain smooth performance. If shifting problems persist, a transmission adaptation reset or software update may be required.
Drivetrain Vibrations and Noises
Some S 450 owners have reported unusual vibrations or clunking noises when accelerating.
These symptoms can be caused by:
Worn engine and transmission mounts
Driveshaft imbalance
Issues with the rear differential
If vibrations increase over time, a thorough inspection of the drivetrain components is necessary to prevent further damage.
Mercedes S-Class W223 S 450 Suspension and Ride Quality Issues
The W223 S-Class features an advanced suspension system designed to deliver a smooth and comfortable ride. However, certain components can develop issues over time, affecting the vehicle’s handling and ride quality.
AIRMATIC Suspension Problems
The AIRMATIC air suspension provides an adjustable ride height and adaptive damping for maximum comfort.
However, some owners have reported issues such as:
Vehicle sagging to one side after being parked overnight
Harsh ride quality or excessive bouncing
Suspension warning messages on the dashboard
These symptoms are often caused by leaking air struts, a failing air compressor, or faulty ride height sensors. If left unaddressed, a malfunctioning air suspension system can lead to further component failures.
Replacing worn-out air struts and ensuring the compressor is functioning properly can help restore ride comfort.
Active Body Control (E-Active Body Control) Malfunctions
The S 450 comes with an optional E-Active Body Control system, which enhances ride comfort and handling.
Some owners have reported malfunctions with this system, including:
Sudden loss of suspension adjustability
Warning messages related to active suspension
Uneven ride height
These issues may stem from faulty sensors, software glitches, or hydraulic system failures. A diagnostic scan can help pinpoint the exact problem, and in many cases, a software update or sensor replacement can fix the issue.
Mercedes S-Class W223 S 450 Electrical and Technology Failures
The W223 S 450 is packed with cutting-edge technology, from the MBUX infotainment system to a suite of driver-assist features. While these innovations enhance the driving experience, they can also be a source of frustration when they fail.
MBUX Infotainment System Glitches
The Mercedes-Benz User Experience (MBUX) is one of the most advanced infotainment systems in the industry.
However, some owners have encountered problems such as:
System freezes or crashes
Unresponsive touchscreens
Bluetooth and Apple CarPlay connectivity issues
These glitches are often related to software bugs. Performing a system reset or updating the software can resolve many of these problems.
If the issues persist, the main control unit may need replacement.
Keyless-Go and Push-Button Start Issues
The Keyless-Go system allows for keyless entry and engine start, but some S 450 owners have experienced problems with:
Doors failing to unlock or lock properly
The push-button start not responding
Intermittent key fob detection issues
These problems can be caused by a weak key fob battery, signal interference, or a faulty keyless entry module.
Replacing the key fob battery is a simple fix, but if the issue persists, the vehicle’s keyless system should be inspected by a professional.
Adaptive Cruise Control and Lane Assist Malfunctions
The W223 S-Class features advanced driver assistance systems such as adaptive cruise control, lane-keeping assist, and automated parking.
Some owners have reported these systems malfunctioning, including:
Unexpected braking when using adaptive cruise control
Inconsistent lane-keeping assistance
Parking sensors providing false readings
These issues are often linked to sensor misalignment or software bugs. A system recalibration or software update usually resolves the problem.
Mercedes S-Class W223 S 450 Cooling System and Overheating Issues
Maintaining optimal engine temperature is critical for the Mercedes S 450's performance and longevity. However, some W223 owners have reported cooling system problems that, if left unresolved, can lead to overheating and serious engine damage.
Coolant Leaks and Radiator Problems
Coolant leaks are a common concern in many high-performance luxury vehicles, including the S 450.
Leaks can occur due to:
Cracked or degraded radiator hoses
A faulty water pump
A failing radiator
Symptoms include low coolant levels, an overheating engine, and visible coolant puddles under the car.
If you notice any of these warning signs, it’s essential to have the cooling system inspected to prevent engine damage.
Thermostat and Water Pump Failures
A malfunctioning thermostat or failing water pump can lead to erratic temperature fluctuations. Owners have reported that in some cases, the engine temperature rises quickly, only to return to normal levels shortly afterward.
A faulty thermostat may get stuck open or closed, affecting coolant circulation, while a failing water pump may reduce coolant flow.
Replacing these components at the first sign of trouble can prevent expensive engine repairs down the line.
Mercedes S-Class W223 S 450 Braking System Concerns
The braking system in the Mercedes S 450 is designed to offer precision and safety, but certain issues can arise that affect braking performance.
Premature Brake Wear
Several owners have reported that the brake pads and rotors wear out faster than expected.
Factors contributing to this issue include:
The vehicle’s weight and high-performance braking system
Frequent stop-and-go traffic
Hard braking habits
Common symptoms of excessive brake wear include squeaking noises, longer stopping distances, and vibrations while braking.
Using high-quality brake components and following a regular maintenance schedule can help extend the life of the braking system.
Brake Assist and Electronic Stability Control (ESC) Issues
The W223 S-Class features an advanced braking system that includes Brake Assist and ESC.
Some owners have reported:
Unexpected braking interventions
Brake system warning messages
ESC system malfunctions during cornering
These issues can stem from faulty sensors, calibration errors, or software glitches. If a warning light appears, having the system scanned for error codes is the best course of action.
Mercedes S-Class W223 S 450 Interior Wear and Technology Failures
The S 450’s cabin is one of the most luxurious in its class, featuring high-quality materials, ambient lighting, and advanced climate control.
However, some owners have encountered durability and functionality issues.
Leather and Interior Trim Wear
Despite its premium build, the interior of the S 450 can show signs of wear over time, particularly in high-touch areas such as:
Seat bolsters and armrests
Steering wheel leather
Center console buttons and trim
Regular cleaning and conditioning of leather surfaces can help preserve their appearance. Using protective coatings on frequently used buttons can prevent premature wear.
Climate Control and Air Conditioning Issues
The climate control system in the W223 is designed for maximum comfort, but some common problems include:
Uneven cooling or weak airflow
Malfunctioning seat ventilation
Climate control buttons becoming unresponsive
These issues are often caused by clogged cabin air filters, refrigerant leaks, or software glitches.
If you experience inconsistent cooling, having the system checked for leaks or sensor faults is recommended.
Mercedes S-Class W223 S 450 Exhaust System and Emission Control Problems
The S 450's exhaust system is designed to meet strict emissions standards, but it can develop issues over time.
Catalytic Converter Failures
A failing catalytic converter can lead to:
Decreased engine performance
Increased fuel consumption
Check engine lights and emissions test failures
Clogging and overheating are common causes of catalytic converter failure.
Regular servicing and ensuring the engine runs efficiently can help prevent costly replacements.
Oxygen Sensor Malfunctions
Faulty oxygen sensors can lead to poor fuel economy, increased emissions, and sluggish performance.
If an oxygen sensor issue is detected, replacing it promptly can improve engine efficiency.
Mercedes S-Class W223 S 450 Long-Term Maintenance and Ownership Considerations
Owning a luxury vehicle like the Mercedes S 450 requires careful attention to maintenance schedules.
Routine Servicing is Essential
Regular oil changes, transmission servicing, and brake inspections help keep the vehicle in peak condition. Using manufacturer-recommended fluids and parts ensures reliability.
Software Updates and Recall Checks
Mercedes frequently releases software updates to fix infotainment glitches, transmission issues, and driver-assistance malfunctions. Staying updated with the latest software can resolve many minor problems.
Additionally, checking for recalls can help address factory defects before they cause significant issues.
Mercedes S-Class W223 S 450 Conclusion
The Mercedes-Benz S-Class W223 S 450 is a masterpiece of luxury and innovation, but it is not without its share of common problems. Owners have reported issues such as mild-hybrid system failures, turbocharger lag, transmission hesitations, AIRMATIC suspension leaks, and infotainment system glitches.
By staying proactive with maintenance and addressing problems early, S 450 owners can enjoy a smooth and luxurious driving experience.
For professional Mercedes-Benz servicing and repairs, visit European Auto Pro 253 Goodwood Road, Kings Park, 5034 South Australia.
Our expert technicians specialize in diagnosing and fixing common S 450 issues, ensuring that your vehicle remains in top condition.