2002 MERCEDES-BENZ S500 W220

Typical onset: 80,000-120,000 mi

Symptoms: Vehicle sits low in the morning or after sitting, Compressor runs constantly or won't shut off, Harsh ride quality, Airmatic warning light, Uneven stance side-to-side

Fix: Compressor failure is most common (4-5 hours labor), but struts leak too—front struts 3-4 hours each, rears 2-3 hours. Many owners convert to Arnott coil springs to eliminate the system entirely (6-8 hours for full conversion). Air lines crack at fittings.

Estimated cost: $1,200-3,500

Typical onset: 100,000-150,000 mi

Symptoms: Metal shavings in oil, Rough idle or vibration that worsens, Check engine light with misfire codes, Knocking or rattling from lower engine, Sudden loss of power or seized engine

Fix: Balance shaft gears strip teeth, sending metal through the engine—destroys bearings, scores cylinder walls, and clogs oil passages. Requires full engine rebuild (40-60 hours) or replacement short block. Many discover this during routine oil change when filter is full of metal. No cost-effective partial fix exists once damage starts.

Estimated cost: $8,000-15,000

Typical onset: 90,000-140,000 mi

Symptoms: Harsh or delayed shifting, Limp mode activation, No upshift past 2nd or 3rd gear, Slipping between gears, Transmission fault message on dash

Fix: 722.6 transmission uses an electronic conductor plate that cracks solder joints—causes erratic shifts or limp mode. Valve body solenoids fail too. Requires dropping transmission (8-12 hours), replacing conductor plate and valve body. Some shops reflash TCU at same time. This is a when-not-if repair on high-mileage examples.

Estimated cost: $2,000-3,800

Typical onset: 70,000-110,000 mi

Symptoms: ABC warning light with 'Stop vehicle, too low' message, Green hydraulic fluid pooling under car, Car drops to bump stops when parked, Rough ride or excessive body roll, Pulsation pump runs constantly

Fix: If equipped with ABC (not all S500s have it), the hydraulic pulsation dampener, front struts, and pressure hoses all leak. Pulsation dampener alone is 6-8 hours labor. Front ABC struts are $1,500+ each plus 4-5 hours labor per side. System uses special hydraulic fluid. This system is the most expensive maintenance item on W220—many owners disable it or sell the car.

Estimated cost: $2,500-7,000

Typical onset: 60,000-100,000 mi

Symptoms: Red brake warning light with 'Visit workshop' message, Hard brake pedal with reduced braking power, ABS and ESP lights illuminated, Brake fluid pump cycling on/off repeatedly

Fix: Early brake-by-wire system with hydraulic pump and electronic control unit that fails—Mercedes issued recalls and extended warranty to 25 years/250k miles but only if owner received recall notice. Otherwise pump/module replacement is 4-6 hours labor. Verify recall status before buying any W220. Once failed, car can still brake but requires much more pedal force.

Estimated cost: $2,000-4,000

Typical onset: 80,000-130,000 mi

Symptoms: Red transmission fluid leaking near radiator area, Milky or pink coolant in overflow tank, Transmission slipping after engine warms up, Clunking when shifting into gear, Visible sagging of transmission

Fix: External transmission oil cooler develops pinhole leaks, mixing coolant and ATF—ruins both systems if not caught early. Cooler replacement is 2-3 hours. Transmission mounts crack and collapse, causing harsh shifts and driveline vibration—mounts are 3-4 hours to replace. Check both when addressing transmission concerns.

Estimated cost: $600-1,500

Symptoms: Navigation screen goes blank or freezes, Radio loses all presets randomly, Amplifier cuts in and out, Telephone system inoperative, Multiple warning messages for unrelated systems

Fix: Fiber optic MOST bus develops breaks or corrosion at connectors—causes bizarre electrical issues across multiple modules. Diagnosis is time-consuming (2-4 hours tracing) and repair depends on location. COMAND head unit itself fails too—used replacements need VIN coding. Aftermarket head units available but lose some functionality.

Estimated cost: $800-2,500