2009 Mercedes-Benz S550

The 2009 Mercedes-Benz S550 is a luxury sedan known for its opulent features, smooth ride, and powerful performance. This model year offered a single engine option: a 5.5-liter V8 engine that produces 382 horsepower and 391 lb-ft of torque. It came standard with a 7-speed automatic transmission. Owners generally appreciate the car’s comfort, technology, and stately presence. Common dislikes often center around high maintenance costs and the complexity of its electronic systems.

Engine

5.5L V8

• Camshaft Adjuster Solenoid Failure
  • Description/Symptoms: Check engine light activation with codes related to camshaft position, rough idle, decreased fuel economy, and potential engine misfires.
  • Solution: Replacement of the faulty camshaft adjuster solenoid(s).
  • Estimated Cost to Fix: $200 - $500+ per solenoid, depending on labor rates and part availability.
  • Recalls: None Found
• Valve Cover Gasket Leaks
  • Description/Symptoms: Oil leaks from the valve cover area, often noticeable by the smell of burning oil and visible oil residue on the engine.
  • Solution: Replacement of the valve cover gaskets.
  • Estimated Cost to Fix: $300 - $800+, depending on labor rates.
  • Recalls: None Found
• Oil Filter Housing Gasket Leaks
  • Description/Symptoms: Oil leaks originating from the oil filter housing area. Can lead to low oil levels and potential engine damage if left unattended.
  • Solution: Replacement of the oil filter housing gasket.
  • Estimated Cost to Fix: $400 - $1000+, depending on labor rates and accessibility.
  • Recalls: None Found

Transmission

7-Speed Automatic (7G-Tronic)

• Torque Converter Issues
  • Description/Symptoms: Shuddering or vibration during acceleration, particularly at lower speeds. May also experience erratic shifting.
  • Solution: Replacement or rebuilding of the torque converter. Transmission fluid flush and filter change.
  • Estimated Cost to Fix: $1,500 - $4,000+
  • Recalls: None Found
• Conductor Plate Failure
  • Description/Symptoms: Erratic shifting, transmission stuck in gear, or failure to shift at all. May also trigger a check engine light.
  • Solution: Replacement of the transmission conductor plate.
  • Estimated Cost to Fix: $800 - $1,500+
  • Recalls: None Found

Suspension

• Airmatic Suspension Compressor Failure
  • Description/Symptoms: The vehicle sits lower than normal, especially after being parked overnight. The Airmatic system may display warning messages.
  • Solution: Replacement of the Airmatic suspension compressor.
  • Estimated Cost to Fix: $800 - $1,500+
  • Recalls: None Found
• Airmatic Strut Failure
  • Description/Symptoms: The vehicle sits unevenly, with one corner noticeably lower than the others. Bouncing or instability when driving.
  • Solution: Replacement of the faulty Airmatic strut(s).
  • Estimated Cost to Fix: $1,000 - $2,500+ per strut.
  • Recalls: None Found
• ABC (Active Body Control) Hydraulic Pump Failure
  • Description/Symptoms: ABC warning lights, stiff or non-existent suspension, difficulty raising or lowering the vehicle.
  • Solution: Replacement of the ABC Hydraulic Pump.
  • Estimated Cost to Fix: $2,000 - $4,000+
  • Recalls: None Found

Electrical

• Electronic Ignition Switch (EIS) Failure
  • Description/Symptoms: Difficulty starting the vehicle, intermittent starting issues, or complete inability to start the car. The key may not turn in the ignition.
  • Solution: Replacement of the EIS module, potentially requiring reprogramming.
  • Estimated Cost to Fix: $800 - $2,000+
  • Recalls: None Found
• Battery Drain Issues
  • Description/Symptoms: The battery frequently drains, especially if the car sits for a few days. Can be caused by a variety of electrical components not shutting down properly.
  • Solution: Diagnosis and repair of the parasitic draw.
  • Estimated Cost to Fix: $100 - $1,000+ (depending on the source of the drain).
  • Recalls: None Found
• COMAND System Malfunctions
  • Description/Symptoms: Freezing, crashing, or unresponsive COMAND system (navigation, audio, climate control).
  • Solution: Software update, replacement of COMAND unit.
  • Estimated Cost to Fix: $200-$2000+, depending on the issue and solution.
  • Recalls: None Found

Exterior

• No Issues Found

Interior

• Sunroof Issues
  • Description/Symptoms: Sunroof fails to open or close properly, makes excessive noise, or gets stuck.
  • Solution: Repair or replacement of sunroof motor, tracks, or other components.
  • Estimated Cost to Fix: $300 - $1,500+
  • Recalls: None Found

Summary

The 2009 Mercedes-Benz S550, while a luxurious and comfortable vehicle, is prone to certain common issues. Suspension problems (particularly with the Airmatic system) and electrical malfunctions are among the most frequently reported. Engine and transmission issues can also occur, leading to significant repair costs. The severity of these problems ranges from minor inconveniences to major mechanical failures, and the cost to fix them can be substantial. Potential buyers should be aware of these potential issues and factor them into their purchasing decision. Thorough inspection by a qualified mechanic is highly recommended before purchasing this vehicle.