2008 Mercedes-Benz S550

The 2008 Mercedes-Benz S550 is a luxury sedan known for its comfortable ride, opulent interior, and advanced technology for its time. The standard engine is a 5.5-liter V8 producing 382 horsepower and 391 lb-ft of torque, paired with a 7-speed automatic transmission (7G-TRONIC). Some owners praise its smooth ride, powerful engine, and luxurious features. Common complaints revolve around expensive maintenance, electrical issues, and the aging air suspension system. Other engine options included a 6.0L V12 (S600, S65 AMG) and a smaller displacement V8 (S450). There was no other transmission option.

Engine

5.5L V8 (M273)

• Camshaft Adjuster Solenoid Failure
  • Description/Symptoms: The engine may experience rough idling, misfires, and a check engine light. Diagnostic Trouble Codes (DTCs) related to camshaft position or timing deviations are often present.
  • Solution: Replacement of the faulty camshaft adjuster solenoid(s).
  • Estimated Cost to Fix: $300 - $800+ depending on the number of solenoids replaced and labor rates.
• Valve Cover Gasket Leaks
  • Description/Symptoms: Oil leaks visible around the valve covers, burning oil smell, and potentially low oil levels.
  • Solution: Replacement of the valve cover gaskets.
  • Estimated Cost to Fix: $400 - $1000+, varying with labor costs and whether additional components like spark plug tube seals are replaced.
• Intake Manifold Cracks/Leaks
  • Description/Symptoms: Rough idle, poor fuel economy, and a possible check engine light. Vacuum leaks can affect engine performance.
  • Solution: Replacement of the intake manifold, or repair of the crack if feasible (though replacement is typically recommended).
  • Estimated Cost to Fix: $800 - $1500+

Transmission

7G-TRONIC (722.9)

• Torque Converter Failure
  • Description/Symptoms: Shuddering or vibration during acceleration, particularly at lower speeds. Hesitation when shifting between gears.
  • Solution: Torque converter replacement.
  • Estimated Cost to Fix: $2000 - $4000+ including labor and fluid.
• Valve Body Issues
  • Description/Symptoms: Harsh or erratic shifting, delayed engagement of gears, slipping between gears, or failure to shift at all.
  • Solution: Valve body replacement or rebuild. In some cases, replacing the conductor plate and solenoids may resolve the issue.
  • Estimated Cost to Fix: $1000 - $3000+, depending on the extent of the repairs.
• Transmission Fluid Leaks (Pilot Bushing)
  • Description/Symptoms: Transmission fluid leaking from the electrical connector on the transmission. Can lead to shifting problems if fluid level drops significantly.
  • Solution: Replacement of the pilot bushing (electrical connector seal).
  • Estimated Cost to Fix: $150 - $400

Suspension

• Airmatic Suspension Failure (Struts/Air Springs)
  • Description/Symptoms: Vehicle sitting low on one or more corners, failure to maintain ride height, error messages on the dashboard related to the Airmatic system, and a rough or bouncy ride. Hissing sounds from the struts indicate leaks.
  • Solution: Replacement of the faulty air strut(s) or air spring(s). In some cases, the air compressor may also need to be replaced if it has been overworked trying to compensate for leaks.
  • Estimated Cost to Fix: $1000 - $2500+ per strut, with compressor replacement potentially adding another $500 - $1500.
• Airmatic Compressor Failure
  • Description/Symptoms: The car takes a long time to raise, or fails to raise completely. Error messages related to the Airmatic system may appear on the dashboard.
  • Solution: Replacement of the Airmatic compressor.
  • Estimated Cost to Fix: $500 - $1500+, depending on the brand and labor.

Electrical

• Battery Drain Issues
  • Description/Symptoms: The battery drains overnight or within a few days of being parked, requiring frequent jump-starts.
  • Solution: Diagnose and repair the source of the parasitic drain. Common culprits include faulty modules, aftermarket electronics, or a failing alternator.
  • Estimated Cost to Fix: $100 - $1000+, depending on the complexity of the issue and the parts needed. Diagnosis can be time-consuming.
• COMAND System Malfunctions
  • Description/Symptoms: The COMAND (Cockpit Management and Data) system, which controls navigation, audio, climate, and other features, may experience freezing, reboots, screen flickering, or complete failure.
  • Solution: Software updates, replacement of the COMAND unit, or repair of faulty wiring.
  • Estimated Cost to Fix: $300 - $2000+, depending on the severity of the problem and whether replacement is necessary.
• Keyless Go Malfunctions
  • Description/Symptoms: The Keyless Go system, which allows for keyless entry and starting, may fail to recognize the key fob, preventing the car from unlocking or starting.
  • Solution: Replacement of the key fob battery, reprogramming the key fob, or replacement of the Keyless Go module.
  • Estimated Cost to Fix: $50 - $500+

Exterior

• Headlight Condensation
  • Description/Symptoms: Moisture buildup inside the headlight housings, reducing visibility and potentially damaging the headlight components.
  • Solution: Resealing the headlight housings or replacing the headlights.
  • Estimated Cost to Fix: $200 - $1000+

Interior

• Sunroof Issues
  • Description/Symptoms: Sunroof failing to open or close properly, making grinding noises, or leaking water.
  • Solution: Repair or replacement of the sunroof motor, tracks, or seals.
  • Estimated Cost to Fix: $300 - $1000+
• Door Lock Actuator Failure
  • Description/Symptoms: Doors failing to lock or unlock with the key fob or interior switches.
  • Solution: Replacement of the faulty door lock actuator.
  • Estimated Cost to Fix: $200 - $600+ per door

Recalls:

• 2007100001 - Side Air Bag Initiator May Fracture
• 2016070002 - Improperly Welded Seat Frame

Summary:

The 2008 Mercedes-Benz S550, while offering luxury and performance, is prone to various issues as it ages. The most significant and expensive problems often involve the Airmatic suspension, transmission, and electrical systems. Engine issues, while less frequent, can still be costly to address. Potential buyers should be aware of these potential problems and factor in maintenance costs when considering this vehicle. The severity of these issues ranges from minor inconveniences to major repairs costing thousands of dollars.