The Mercedes-Benz S-Class W223 S 350 represents the latest generation of luxury sedans, offering cutting-edge technology, refined engineering, and an unparalleled driving experience. As a flagship model, the W223 S 350 sets high standards in performance, comfort, and innovation. However, like any complex and high-tech vehicle, it is not without its flaws.
Owners and potential buyers should be aware of certain recurring issues that have been reported in the W223 S 350. While Mercedes-Benz has made significant advancements in durability and reliability, several problems related to the engine, transmission, suspension, electronics, and interior components have emerged.
In this comprehensive guide, we will explore the most common problems of the Mercedes S 350 W223, their causes, symptoms, and possible solutions. Understanding these issues can help owners maintain their vehicles better and make informed decisions when purchasing a used model.
Mercedes S-Class W223 S 350 Engine and Performance Issues
The W223 S 350 is equipped with a 3.0L inline-6 turbocharged engine, delivering smooth performance and efficiency. While this engine is known for its refinement, some mechanical issues have been reported over time.
Turbocharger Problems
The turbocharger in the S 350 enhances power output and fuel efficiency. However, it can develop issues such as excessive oil consumption, carbon buildup, and actuator failures. Owners have reported loss of power, sluggish acceleration, and unusual whining noises from the engine bay.
A failing turbocharger can lead to increased fuel consumption and black smoke from the exhaust. Regular maintenance, including oil changes with high-quality synthetic oil, can help prolong the lifespan of the turbo. If turbo problems arise, professional inspection and possible replacement may be required.
Timing Chain Tensioner Wear
The timing chain ensures synchronized movement between the engine’s camshaft and crankshaft. In some cases, the timing chain tensioner in the W223 S 350 may wear out prematurely, leading to rattling noises on startup and potential engine timing issues. If not addressed, timing chain failure can result in severe engine damage.
Replacing the timing chain tensioner at the first sign of wear is essential to prevent catastrophic engine failure. Regular oil changes with manufacturer-recommended oil can also help maintain chain lubrication and reduce wear.
Oil Leaks and High Oil Consumption
Several W223 S 350 owners have reported excessive oil consumption and leaks. Common leak sources include the valve cover gasket, oil pan gasket, and turbocharger seals. If oil levels drop too low, it can cause increased engine wear and even overheating.
Symptoms of oil leaks include visible oil spots under the vehicle, a burning oil smell, and low oil warning lights. Routine inspections and timely gasket replacements can help prevent these problems from escalating.
Mercedes S-Class W223 S 350 Transmission Problems
The Mercedes S 350 W223 features a 9-speed (9G-Tronic) automatic transmission designed for smooth and efficient shifts. While generally reliable, some owners have experienced transmission-related issues that affect drivability.
Rough or Delayed Shifting
One of the most common complaints is rough shifting or delayed gear engagement. Some drivers have noticed hesitation when accelerating, harsh gear changes, or a sluggish response from the gearbox. These problems are often linked to outdated transmission software, low fluid levels, or mechanical wear.
Regular transmission fluid changes every 60,000 km can help prevent shifting issues. In some cases, a software update from the dealership can resolve transmission hesitation problems.
Torque Converter Issues
The torque converter in the W223 S 350 has been known to develop shuddering issues, particularly at low speeds. This manifests as a vibration or juddering sensation when accelerating. If ignored, it can lead to long-term transmission damage.
A full transmission fluid flush using OEM-approved fluid often resolves torque converter shudder. If the problem persists, torque converter replacement may be necessary.
Mercedes S-Class W223 S 350 Suspension and Ride Comfort Issues
Mercedes-Benz has equipped the W223 S-Class with an advanced E-Active Body Control suspension system to provide superior ride comfort. However, this system is complex and prone to certain issues.
AIRMATIC Suspension Failures
The AIRMATIC air suspension system allows for adjustable ride height and adaptive damping, ensuring a smooth ride. However, some owners have reported air strut failures, leading to sagging suspension, excessive bouncing, or difficulty maintaining proper ride height.
Air suspension issues are typically caused by leaking air struts, a failing air compressor, or sensor malfunctions. If left unrepaired, a leaking air strut can overwork the compressor, leading to a costly replacement. Routine inspections can help detect early signs of suspension problems.
Steering and Handling Issues
Some W223 S 350 owners have complained about vague steering feedback and excessive play in the steering wheel. This can be caused by worn control arm bushings, faulty electronic steering components, or misalignment.
Symptoms include clunking noises when turning, uneven tire wear, and poor handling stability. Replacing worn suspension components and performing regular wheel alignments can improve steering precision and handling.
Mercedes S-Class W223 S 350 Electrical and Technology Problems
The S 350 W223 is packed with advanced electronics, including the latest MBUX infotainment system, driver assistance features, and numerous sensors. While these technologies enhance convenience, they can also be sources of frustration when malfunctions occur.
MBUX Infotainment System Freezing
The MBUX system is one of the most advanced infotainment systems in the industry, but it is not immune to glitches. Owners have reported issues such as touchscreen freezing, unresponsive controls, and unexpected reboots.
These problems are often software-related and can be resolved with a system reset or software update. If the issue persists, faulty hardware may need to be replaced.
Keyless Entry and Push-Button Start Failures
Some owners have experienced problems with the Keyless-Go system, where the vehicle fails to recognize the key fob or does not start properly. This can be caused by a weak key fob battery, interference from other electronic devices, or a malfunctioning keyless entry module.
Replacing the key fob battery is a simple first step. If the issue continues, reprogramming the key or inspecting the keyless entry system may be necessary.
Adaptive Cruise Control and Driver Assistance Malfunctions
The W223 S 350 comes equipped with advanced driver assistance systems such as adaptive cruise control, lane-keeping assist, and automatic emergency braking. Some owners have reported intermittent malfunctions in these systems, such as sudden deactivation, false warnings, or unresponsive sensors.
Dirty or obstructed radar sensors and cameras can cause these issues. Cleaning the sensors and ensuring the software is updated can often resolve the problem. If the issue persists, recalibration or sensor replacement may be required.
Mercedes S-Class W223 S 350 Cooling System and Overheating Issues
The cooling system in the Mercedes-Benz S 350 W223 plays a crucial role in maintaining optimal engine temperatures. However, some owners have encountered issues related to coolant leaks, radiator failures, and thermostat malfunctions.
Coolant Leaks and Low Coolant Levels
Coolant leaks are a common problem in high-performance engines like the one found in the S 350. Over time, the plastic and rubber components of the cooling system, such as the coolant hoses, expansion tank, and radiator seals, can deteriorate, leading to leaks.
Signs of coolant leaks include:
Puddles of coolant under the car
Overheating warnings on the dashboard
A sweet smell coming from the engine bay
Ignoring coolant leaks can result in severe overheating and potential engine damage. Regular inspections and timely replacement of worn-out hoses and seals can help prevent these issues.
Water Pump and Thermostat Failures
The water pump circulates coolant through the engine, while the thermostat regulates its flow. In some cases, the water pump in the W223 S 350 can fail prematurely due to wear, causing coolant circulation issues and overheating.
A faulty thermostat, on the other hand, can get stuck in an open or closed position, leading to fluctuating engine temperatures.
Symptoms of thermostat failure include erratic temperature readings and poor heater performance. Replacing these components as part of routine maintenance can prevent cooling system failures.
Mercedes S-Class W223 S 350 Braking System Issues
The Mercedes S 350 W223 is equipped with an advanced braking system, ensuring optimal stopping power. However, some braking-related issues have been reported by owners.
Premature Brake Pad and Rotor Wear
Due to the vehicle’s weight and high-performance braking system, the brake pads and rotors tend to wear out faster than expected. This leads to increased maintenance costs and frequent replacements.
Common symptoms of excessive brake wear include:
Squealing or grinding noises when braking
Vibration or pulsation in the brake pedal
Increased braking distance
Using high-quality aftermarket brake pads and rotors can sometimes extend lifespan and reduce wear. Additionally, driving habits, such as avoiding aggressive braking, can help prolong brake life.
Brake Assist and ABS Malfunctions
Some S 350 W223 owners have reported problems with the Anti-lock Braking System (ABS) and Brake Assist functions. These issues often stem from faulty wheel speed sensors, brake fluid contamination, or software glitches.
Symptoms of ABS failure include:
ABS warning light on the dashboard
Brakes locking up during emergency stops
Reduced traction control performance
If ABS or Brake Assist malfunctions occur, a professional diagnostic scan is necessary to pinpoint the issue. Replacing faulty sensors or updating the vehicle’s software can often resolve these problems.
Mercedes S-Class W223 S 350 Interior Wear and Comfort Issues
The W223 S-Class is designed to offer supreme comfort and luxury, but some interior components may not hold up as well as expected over time.
Leather Seat Wear and Tear
Despite using premium leather, the seat bolsters in the W223 S 350 can experience excessive wear, especially in high-mileage vehicles. Drivers frequently entering and exiting the car place stress on the leather, leading to cracking and fading.
To maintain the interior’s premium look, regular conditioning with high-quality leather treatment products is recommended. In severe cases, reupholstering may be necessary to restore the cabin’s elegance.
Ambient Lighting and Electronic Seat Adjustments Malfunctions
The Mercedes-Benz S-Class is known for its sophisticated ambient lighting and electronically adjustable seats. However, some owners have reported that the ambient lighting flickers or stops working altogether due to software issues or faulty wiring.
Additionally, seat adjustment controls may become unresponsive, often caused by motor failures or electrical faults. Resetting the vehicle’s electronic systems or replacing defective seat motors can resolve these problems.
Mercedes S-Class W223 S 350 Fuel System and Injector Problems
The direct-injection fuel system in the Mercedes S 350 W223 improves efficiency but can also develop issues over time.
High-Pressure Fuel Pump (HPFP) Failure
The high-pressure fuel pump is responsible for delivering fuel at the required pressure for optimal combustion.
Some owners have reported HPFP failures, leading to symptoms such as:
Difficulty starting the car
Engine hesitation under acceleration
Increased fuel consumption
Replacing a failing HPFP promptly can prevent further engine damage. Additionally, using high-quality fuel and fuel additives can help reduce wear on the pump.
Carbon Buildup on Intake Valves
Direct-injection engines are prone to carbon buildup on the intake valves since fuel does not directly clean them during operation. Over time, this buildup can restrict airflow and reduce engine efficiency.
Symptoms of carbon buildup include:
Rough idling
Reduced throttle response
Engine misfires
Periodic intake valve cleaning using walnut blasting or chemical treatments can help restore engine performance and prevent drivability issues.
Mercedes S-Class W223 S 350 Exhaust System and Emission Concerns
The exhaust system in the W223 S 350 is designed to meet modern emission standards, but certain components may develop faults over time.
Catalytic Converter Clogging
The catalytic converter helps reduce harmful emissions but can become clogged due to excessive carbon buildup or engine misfires. A clogged catalytic converter can lead to poor acceleration, check engine light warnings, and increased fuel consumption.
If catalytic converter failure is detected, replacement is necessary to maintain performance and meet emission standards.
Diesel Particulate Filter (DPF) Issues (For Diesel Models)
For S 350 diesel variants, the Diesel Particulate Filter (DPF) is a crucial component for reducing emissions. However, it can become clogged, especially in vehicles frequently driven in stop-and-go traffic.
Symptoms of a clogged DPF include:
Reduced engine power
Increased fuel consumption
DPF warning light on the dashboard
To prevent DPF clogging, regular long drives at highway speeds help initiate regeneration, burning off accumulated soot. If problems persist, professional cleaning or DPF replacement may be required.
Mercedes S-Class W223 S 350 Long-Term Maintenance and Ownership Considerations
Owning a luxury sedan like the W223 S 350 requires a proactive approach to maintenance. Many common issues can be prevented or mitigated with regular servicing.
Regular Servicing and Fluid Changes
Routine maintenance, including oil changes, transmission fluid changes, and brake inspections, ensures longevity and performance. Using manufacturer-recommended fluids and parts is essential for preventing premature wear.
Software Updates and Recalls
Mercedes-Benz frequently releases software updates to improve system performance and fix bugs. Ensuring that the vehicle’s software is up to date can resolve minor electronic issues. Additionally, checking for recalls and service bulletins can help address any factory defects.
Mercedes S-Class W223 S 350 Conclusion
The Mercedes-Benz S-Class W223 S 350 is a masterpiece of engineering, offering advanced technology, luxury, and performance. However, it is not immune to issues, including turbocharger failures, transmission hesitations, air suspension leaks, and electronic malfunctions.
By staying proactive with maintenance and addressing problems early, owners can ensure their S 350 remains in top condition for years to come.
For expert Mercedes-Benz servicing and repairs, visit European Auto Pro 253 Goodwood Road, Kings Park, 5034 South Australia.
Our skilled technicians specialize in diagnosing and repairing common S-Class issues, ensuring a smooth and worry-free ownership experience.