2012 Mercedes-Benz S350

The 2012 Mercedes-Benz S350 is a luxury sedan known for its comfort, advanced technology, and smooth ride. The S350, in particular, features a 3.0-liter turbodiesel V6 engine producing 255 horsepower and 457 lb-ft of torque. Other engine options available in the 2012 S-Class range include gasoline V6, V8, and V12 engines. All engines are typically paired with a 7-speed automatic transmission. Owners often praise the S350 for its fuel efficiency (for a car of its size), opulent interior, and sophisticated features. Downsides often cited include potentially high maintenance costs and the complexity of its electronic systems.

Engine

3.0L Turbodiesel V6

• Oil Cooler Seal Leaks
  • Description/Symptoms: Oil leaks are observed near the oil cooler. This can lead to a loss of oil and potential engine damage if left unaddressed. Burning oil smell may be present.
  • Solution: Replace the oil cooler seals.
  • Estimated Cost to Fix: $300 - $600+
• Glow Plug Failure
  • Description/Symptoms: Difficulty starting, especially in cold weather. The engine may run rough or have reduced power. A check engine light may illuminate.
  • Solution: Replace the faulty glow plug(s).
  • Estimated Cost to Fix: $150 - $400+
  • Recalls: None Found

Transmission

7G-Tronic (7-Speed Automatic)

• Torque Converter Failure
  • Description/Symptoms: Shuddering or vibration during acceleration, especially at lower speeds. Hesitation or slipping during gear changes.
  • Solution: Replace the torque converter.
  • Estimated Cost to Fix: $1,500 - $3,000+
  • Recalls: None Found
• Valve Body Issues
  • Description/Symptoms: Harsh or erratic shifting, delayed engagement of gears, or getting stuck in a gear.
  • Solution: Replace or rebuild the valve body.
  • Estimated Cost to Fix: $800 - $2,000+
  • Recalls: None Found

Suspension

• Airmatic Suspension Compressor Failure
  • Description/Symptoms: The car sits lower than normal, especially on one side. The suspension may not adjust properly, leading to a rough ride. The air suspension warning light may illuminate.
  • Solution: Replace the air suspension compressor.
  • Estimated Cost to Fix: $800 - $1,500+
  • Recalls: None Found
• Airmatic Strut Leaks
  • Description/Symptoms: Same symptoms as compressor failure, but often localized to a specific corner of the car. Hissing sound may be audible near the affected strut.
  • Solution: Replace the leaking air strut.
  • Estimated Cost to Fix: $1,000 - $2,000+ per strut
  • Recalls: None Found

Electrical

• Battery Drain Issues
  • Description/Symptoms: The battery drains quickly, especially when the car is not in use. Difficulty starting the car.
  • Solution: Diagnose and repair the parasitic drain. Common culprits include the COMAND system, door control modules, and seat control modules.
  • Estimated Cost to Fix: $100 - $1000+ (depending on the source of the drain)
  • Recalls: None Found
• COMAND System Malfunctions
  • Description/Symptoms: The COMAND screen may freeze, reboot unexpectedly, or fail to display information. Buttons may become unresponsive.
  • Solution: Software update, replacement of the COMAND unit.
  • Estimated Cost to Fix: $200 - $2000+
  • Recalls: None Found

Exterior

• Sunroof Issues
  • Description/Symptoms: Sunroof getting stuck, making noise when operating, or not closing completely.
  • Solution: Clean and lubricate the sunroof tracks. Repair or replace damaged components (motor, cables, etc.).
  • Estimated Cost to Fix: $100 - $800+
  • Recalls: None Found

Interior

• Seat Heater Failure
  • Description/Symptoms: Seat heater not working or only working intermittently.
  • Solution: Replace the seat heater element or control module.
  • Estimated Cost to Fix: $200 - $600+ per seat
  • Recalls: None Found

Summary

The 2012 Mercedes-Benz S350, while a luxurious and comfortable vehicle, can present owners with several common issues. Engine problems, particularly oil leaks and glow plug failures, are relatively common and can be costly to address. The 7G-Tronic transmission can experience torque converter and valve body issues leading to poor driveability. Suspension problems involving the Airmatic system are also frequently reported, potentially leading to an uncomfortable ride and significant repair bills. Electrical gremlins, such as battery drain and COMAND system malfunctions, can add to the ownership costs. Interior components like seat heaters are also prone to failure. The severity of these issues varies, but the potential for expensive repairs should be considered when purchasing or maintaining a 2012 S350.