2009 Mercedes-Benz SLK55 AMG

The 2009 Mercedes-Benz SLK55 AMG is a high-performance roadster featuring a hand-built 5.5-liter naturally aspirated V8 engine producing 355 horsepower and 376 lb-ft of torque, paired with a 7G-Tronic seven-speed automatic transmission. While appreciated for its potent engine, sporty handling, and retractable hardtop, some owners have reported issues. Potential downsides include higher running costs due to the AMG engine and complex systems, as well as the potential for age-related wear and tear on components. Other engine options available for the 2009 SLK Class include the SLK280/300 with a 3.0L V6 and the SLK350 with a 3.5L V6. The SLK280/300 was offered with a 6-speed manual or 7G-Tronic 7-speed automatic. The SLK350 was offered with the 7G-Tronic 7-speed automatic.

Engine

5.5L M113 V8

• Camshaft Adjuster Solenoid Failure
  • Description/Symptoms: Engine misfires, rough idling, check engine light illumination. Often related to oil contamination.
  • Solution: Replace the faulty camshaft adjuster solenoid. Perform an oil change using the recommended oil type and filter.
  • Estimated Cost to Fix: $200 - $500+
  • Recalls: None Found
• Valve Cover Gasket Leaks
  • Description/Symptoms: Oil leaks around the valve covers, visible oil residue, burning oil smell.
  • Solution: Replace the valve cover gaskets.
  • Estimated Cost to Fix: $300 - $700+
  • Recalls: None Found

Transmission

7G-Tronic (722.9)

• Torque Converter Failure
  • Description/Symptoms: Shuddering at low speeds, especially during acceleration. Can lead to complete transmission failure if not addressed.
  • Solution: Replace the torque converter. Flush the transmission fluid and replace the filter.
  • Estimated Cost to Fix: $2,000 - $4,000+
  • Recalls: None Found
• Valve Body Issues
  • Description/Symptoms: Harsh or delayed shifting, gear slippage, getting stuck in gear.
  • Solution: Replace or rebuild the valve body. Flush the transmission fluid and replace the filter.
  • Estimated Cost to Fix: $1,500 - $3,000+
  • Recalls: None Found
• Conductor Plate Failure
  • Description/Symptoms: Transmission stuck in limp mode, inability to shift gears, error codes related to speed sensors or solenoids.
  • Solution: Replace the conductor plate inside the transmission.
  • Estimated Cost to Fix: $800 - $1500+
  • Recalls: None Found

Suspension

• Air Suspension Compressor Failure (If Equipped)
  • Description/Symptoms: Vehicle sagging, inability to maintain ride height, loud compressor operation, suspension malfunction warning light.
  • Solution: Replace the air suspension compressor. Check for leaks in the air lines and struts.
  • Estimated Cost to Fix: $800 - $1,500+
  • Recalls: None Found
• Air Strut Leaks (If Equipped)
  • Description/Symptoms: Vehicle sagging, especially overnight, hissing sound from the suspension, rough ride.
  • Solution: Replace the leaking air strut(s).
  • Estimated Cost to Fix: $800 - $2,000+ per strut
  • Recalls: None Found
• ABC (Active Body Control) Pump Failure (If Equipped)
  • Description/Symptoms: Ride height issues, stiff suspension, warning lights, fluid leaks.
  • Solution: Replace the ABC pump and flush the system.
  • Estimated Cost to Fix: $1,500 - $3,000+
  • Recalls: None Found

Electrical

• Electronic Steering Lock (ESL) Failure
  • Description/Symptoms: Key not recognized, unable to start the vehicle, steering wheel locked.
  • Solution: Replace or repair the ESL unit.
  • Estimated Cost to Fix: $800 - $1,500+
  • Recalls: None Found
• SAM (Signal Acquisition Module) Failures
  • Description/Symptoms: Various electrical issues, including lighting malfunctions, wiper problems, or inability to start the vehicle.
  • Solution: Diagnose the specific SAM module that is failing and replace it.
  • Estimated Cost to Fix: $500 - $1,200+
  • Recalls: None Found
• Battery Drain
  • Description/Symptoms: Car battery frequently dies.
  • Solution: Parasitic draw testing to identify the circuit or component draining the battery.
  • Estimated Cost to Fix: $150 - $500+ to diagnose, plus the cost of parts to replace the failed component.
  • Recalls: None Found

Exterior

• Retractable Hardtop Malfunctions
  • Description/Symptoms: Top not opening or closing smoothly, getting stuck, error messages on the dashboard.
  • Solution: Diagnose and repair the hydraulic system, including the pump, cylinders, and lines. Check the sensors and switches.
  • Estimated Cost to Fix: $500 - $3,000+ depending on the component.
  • Recalls: None Found

Interior

• COMAND System Issues
  • Description/Symptoms: Screen freezing, navigation problems, audio malfunctions.
  • Solution: Software update or replacement of the COMAND unit.
  • Estimated Cost to Fix: $300 - $2,000+
  • Recalls: None Found
• Seat Heater Failure
  • Description/Symptoms: Seat heater not working or only working intermittently.
  • Solution: Replace the seat heater element.
  • Estimated Cost to Fix: $300 - $800+
  • Recalls: None Found

Summary

The 2009 Mercedes-Benz SLK55 AMG, while offering a thrilling driving experience, can present owners with a range of issues. Engine and transmission problems, especially concerning the 7G-Tronic transmission, are notable. Suspension issues, particularly those related to the air suspension or ABC systems, can also lead to significant repair costs. Electrical issues can be frustrating and costly to diagnose. While some issues are relatively minor, others can be quite expensive to repair, making it important for potential buyers to carefully inspect the vehicle and obtain a pre-purchase inspection from a qualified mechanic familiar with Mercedes-Benz vehicles.