2004 MERCEDES-BENZ S600

Typical onset: 80,000-120,000 mi

Symptoms: Car drops to the ground after sitting overnight, ABC warning light with suspension malfunction message, Uneven ride height side-to-side, Hydraulic fluid leaks under front of vehicle

Fix: ABC pump failure is most common, requires 6-8 hours labor. Strut failures add another 4-6 hours per corner. Many shops won't touch ABC systems due to complexity and liability. Pump replacement is engine-out on some configurations due to packaging.

Estimated cost: $3,500-8,000

Typical onset: 90,000-150,000 mi

Symptoms: White smoke from exhaust on cold start, Milky oil on dipstick, Rapid coolant loss with no external leaks, Cylinder misfire codes, Catastrophic bearing noise if ignored

Fix: Failed head gaskets or cracked cylinder heads allow coolant into cylinders, washing cylinder walls and destroying bearings. Requires both heads off minimum (18-24 hours), often progresses to full short block replacement (40-50 hours) if coolant contaminated the oil system. Engine must come out for proper access.

Estimated cost: $12,000-25,000

Typical onset: 70,000-110,000 mi

Symptoms: Transmission fluid in coolant reservoir (strawberry milkshake color), Transmission slipping or delayed engagement, Overheating transmission, Coolant loss

Fix: The 722.6 transmission cooler is integrated into the radiator with a notorious valve that fails, allowing cross-contamination. Requires radiator replacement, transmission fluid flush, and often transmission rebuild if coolant entered trans (20-30 hours total). This failure destroys transmissions quickly.

Estimated cost: $4,500-9,000

Typical onset: 60,000-100,000 mi

Symptoms: Compressor runs constantly, Vehicle sags overnight or when parked, Airmatic malfunction warning, Compressor cycling every few minutes while driving

Fix: Compressor relay failure causes continuous running and premature compressor death. Air lines crack at fittings. Compressor replacement is 3-4 hours, air struts are 2-3 hours each. Valve block failures add another $2k in parts alone.

Estimated cost: $2,000-5,000

Typical onset: 100,000-140,000 mi

Symptoms: Metallic rattle on cold start that disappears when warm, Loss of boost pressure, P0299 underboost codes, Reduced power at higher RPMs

Fix: Wastegate actuator arms wear and rattle, eventually sticking. Each turbo requires 8-12 hours labor due to tight V12 packaging. Turbos are not available separately from manifolds on early production cars, tripling parts cost. Both sides usually fail within 20k miles of each other.

Estimated cost: $4,000-7,000

Typical onset: 50,000-90,000 mi

Symptoms: Battery repeatedly dies despite new battery, Alternator warning light, Electrical gremlins (window, seat, radio issues), Voltage fluctuations visible on dash gauge

Fix: Dual alternators ($800 each) and the battery control module ($1,200) fail regularly. Battery is in trunk under floor, control module is under passenger seat. Alternator access requires removing undertray and multiple accessory belts. 4-6 hours labor for both alternators.

Estimated cost: $2,500-4,500

Symptoms: Red brake warning light with stop vehicle message, Complete loss of power brake assist, Brake pedal goes to floor or becomes extremely hard, ABS and ESP lights illuminated

Fix: The SBC brake-by-wire system has a known accumulator failure that causes complete brake system shutdown. Mercedes issued a recall extending warranty to 25 years/250k miles on SBC unit only, but labor (3-4 hours) is owner's responsibility outside original warranty. Independent shops often can't diagnose or obtain parts.

Estimated cost: $0-1,200