2004 Mercedes-Benz SL600

The 2004 Mercedes-Benz SL600 is a luxurious roadster known for its powerful V12 engine and retractable hardtop. Other engine options for this model year included the SL500 with a 5.0L V8 and the SL55 AMG with a supercharged 5.4L V8. The SL600 boasts a 5.5L twin-turbocharged V12 engine producing 493 horsepower and 590 lb-ft of torque. Owners generally appreciate the smooth ride, opulent interior, and effortless acceleration. Some common complaints include the complexity of the systems leading to expensive repairs, electrical gremlins, and the high cost of maintenance.

Engine

5.5L Twin-Turbocharged V12 (M275)

• Coil Pack Failure
  • Description/Symptoms: Misfires, rough idling, check engine light. Often caused by heat and age.
  • Solution: Replace faulty coil pack(s).
  • Estimated Cost to Fix: $300 - $600+ per coil pack (parts and labor)
  • Recalls: None Found
• ABC (Active Body Control) System Leaks and Failures
  • Description/Symptoms: The ABC system utilizes engine power to maintain ride height and control body roll. High pressure hydraulic lines leak, pump failure, strut failure. The car may sag or lean, ride height may be uneven, warning lights on dash. Can cause catastrophic failure causing the car to be undriveable.
  • Solution: Replace leaking hoses, faulty pump, or failing struts. Flush and refill ABC system fluid.
  • Estimated Cost to Fix: $500 - $2000+ per component (parts and labor). Complete system overhaul can exceed $5000.
  • Recalls: None Found
• Turbocharger Issues
  • Description/Symptoms: Loss of power, excessive smoke, whining noises from the turbochargers. Potential oil leaks.
  • Solution: Replace or rebuild faulty turbochargers. Inspect and replace oil feed and drain lines.
  • Estimated Cost to Fix: $2500 - $6000+ (parts and labor)
  • Recalls: None Found

Transmission

5-Speed Automatic (722.6)

• Transmission Conductor Plate Failure
  • Description/Symptoms: Erratic shifting, failure to shift, getting stuck in gear (limp mode). Check engine light illuminated.
  • Solution: Replace the conductor plate inside the transmission. Requires dropping the transmission pan and valve body.
  • Estimated Cost to Fix: $800 - $1500+ (parts and labor)
  • Recalls: None Found
• Torque Converter Failure
  • Description/Symptoms: Shuddering during shifting, abnormal noises while shifting, slipping between gears.
  • Solution: Replace the torque converter.
  • Estimated Cost to Fix: $1500 - $3000+ (parts and labor)
  • Recalls: None Found

Suspension

• ABC (Active Body Control) System Issues
  • Description/Symptoms: As mentioned above, the ABC system is prone to leaks, pump failures, and strut failures. The car may sag or lean, ride height may be uneven, warning lights on dash.
  • Solution: Replace leaking hoses, faulty pump, or failing struts. Flush and refill ABC system fluid.
  • Estimated Cost to Fix: $500 - $2000+ per component (parts and labor). Complete system overhaul can exceed $5000.
  • Recalls: None Found

Electrical

• Electronic Stability Program (ESP) / ABS Issues
  • Description/Symptoms: Warning lights illuminated on the dash, including ESP, ABS, and brake warning lights. Malfunctions in the braking system.
  • Solution: Diagnose and replace faulty wheel speed sensors, yaw sensors, or the ESP control module.
  • Estimated Cost to Fix: $300 - $1500+ (parts and labor), depending on the component needing replacement.
  • Recalls: None Found
• Instrument Cluster Problems
  • Description/Symptoms: Pixels missing from the display, intermittent flickering, or complete failure of the instrument cluster.
  • Solution: Repair or replace the instrument cluster.
  • Estimated Cost to Fix: $500 - $1500+ (parts and labor).
  • Recalls: None Found
• Retractable Hardtop Issues
  • Description/Symptoms: The top may fail to open or close properly, get stuck mid-cycle, or make unusual noises. Caused by hydraulic pump failure, sensor malfunctions, or issues with the locking mechanisms.
  • Solution: Diagnose and repair or replace faulty components, including the hydraulic pump, sensors, and locking mechanisms.
  • Estimated Cost to Fix: $500 - $3000+ (parts and labor), depending on the complexity of the repair.
  • Recalls: None Found

Exterior

• Retractable Hardtop Seal Leaks
  • Description/Symptoms: Water leaks into the cabin, especially around the roof joints and windows.
  • Solution: Replace worn or damaged seals. Adjust roof alignment.
  • Estimated Cost to Fix: $200 - $1000+ (parts and labor)
  • Recalls: None Found

Interior

• Seat Control Module Failure
  • Description/Symptoms: Seats may not adjust properly, memory functions may not work, or the seat may be stuck in one position.
  • Solution: Replace the faulty seat control module.
  • Estimated Cost to Fix: $400 - $1000+ (parts and labor)
  • Recalls: None Found

Summary

The 2004 Mercedes-Benz SL600, while a luxurious and powerful vehicle, is prone to a number of issues that can be costly to repair. The most significant problems revolve around the engine (coil packs, turbochargers), transmission (conductor plate), ABC suspension system, electrical systems (ESP/ABS, instrument cluster, hardtop), and retractable hardtop seals. The severity of these issues ranges from minor inconveniences to major mechanical failures that can render the car undrivable. Estimated repair costs can vary widely depending on the specific problem, but owners should be prepared for potentially expensive repairs, particularly related to the ABC system and the V12 engine.