2004 Mercedes-Benz S500

The 2004 Mercedes-Benz S500 is a luxury sedan known for its smooth ride, opulent interior, and advanced technology for its time. The S500 was equipped with a 5.0L M113 V8 engine that produced 302 horsepower and 339 lb-ft of torque. Other engine options available included a 3.2L V6 in the S350, a 4.3L V8 in the S430, a 5.5L V12 in the S600, and a 5.4L supercharged V8 in the S55 AMG. All engine options were paired with a 5-speed automatic transmission. Owners generally appreciate the comfort and prestige of the S-Class, but common complaints revolve around the complexity of the vehicle and the high cost of repairs, especially with the air suspension and electronic systems.

Engine

5.0L M113 V8

• Oil Leaks
  • Description/Symptoms: Oil leaks can occur from various locations, most commonly the valve cover gaskets, rear main seal, and oil filter housing. Symptoms include visible oil leaks on the engine or ground, and a burning oil smell.
  • Solution: Replace the leaking gasket or seal.
  • Estimated Cost to Fix: $150 - $500+ depending on the location and severity of the leak.
  • Recalls: None Found
• Failed Mass Air Flow (MAF) Sensor
  • Description/Symptoms: Rough idle, poor acceleration, and a check engine light.
  • Solution: Replace the MAF sensor.
  • Estimated Cost to Fix: $150 - $300+
  • Recalls: None Found

Transmission

5-Speed Automatic (722.6)

• Torque Converter Failure
  • Description/Symptoms: Shuddering or vibrations during acceleration, especially at lower speeds. Can also cause stalling.
  • Solution: Replace the torque converter.
  • Estimated Cost to Fix: $800 - $1500+
  • Recalls: None Found
• Transmission Conductor Plate Failure
  • Description/Symptoms: Erratic shifting, getting stuck in one gear (limp mode), or failure to shift at all. Check engine light will illuminate.
  • Solution: Replace the transmission conductor plate.
  • Estimated Cost to Fix: $500 - $1000+
  • Recalls: None Found

Suspension

• Airmatic Suspension Failure
  • Description/Symptoms: The vehicle may sag on one or more corners, the ride may become excessively bumpy, or the Airmatic compressor may run constantly. Dashboard warning lights will likely illuminate.
  • Solution: Diagnose the specific component failure (air spring, strut, compressor, valve block) and replace the faulty part.
  • Estimated Cost to Fix: $500 - $2000+ per corner or component, depending on what needs replacing. A compressor replacement can cost $500-$1000.
  • Recalls: None Found

Electrical

• Battery Drain
  • Description/Symptoms: The battery drains overnight or within a few days of non-use. Can be caused by a variety of issues, including a faulty voltage regulator, a malfunctioning module not shutting down properly, or parasitic draw from aftermarket accessories.
  • Solution: Diagnose and repair the source of the battery drain. This may involve using a multimeter to identify the circuit causing the drain.
  • Estimated Cost to Fix: $100 - $1000+, depending on the cause.
  • Recalls: None Found
• SAM (Signal Acquisition Module) Failure
  • Description/Symptoms: Various electrical malfunctions, such as non-functioning lights, wipers, or other accessories. Can also cause communication errors within the vehicle’s electronic systems.
  • Solution: Replace the faulty SAM unit.
  • Estimated Cost to Fix: $500 - $1200+
  • Recalls: None Found

Exterior

• Rust
  • Description/Symptoms: Rust can appear on various body panels, especially around the wheel wells, door edges, and trunk lid.
  • Solution: Repair or replace the rusted panels.
  • Estimated Cost to Fix: $200 - $2000+ per panel, depending on the severity.
  • Recalls: None Found

Interior

• Sunroof Issues
  • Description/Symptoms: The sunroof may become stuck, make unusual noises, or leak.
  • Solution: Repair or replace the sunroof mechanism.
  • Estimated Cost to Fix: $300 - $1000+
  • Recalls: None Found
• Command System Malfunctions
  • Description/Symptoms: The COMAND system (navigation, audio, climate control) may freeze, reboot, or display error messages.
  • Solution: Depending on the cause, may require software update, replacement of the COMAND unit, or repair of associated wiring.
  • Estimated Cost to Fix: $200 - $1500+
  • Recalls: None Found

Summary

The 2004 Mercedes-Benz S500 is a luxurious vehicle that, unfortunately, is prone to a number of common issues as it ages. The most prevalent concerns revolve around the Airmatic suspension, electrical systems, and the transmission. Repair costs can range from relatively minor fixes to very expensive overhauls, potentially making the ownership experience costly. Potential buyers should have the car inspected by a qualified mechanic specializing in Mercedes-Benz vehicles prior to purchase to identify any existing or potential problems.