The 2017 S600 with the M279 6.0L twin-turbo V12 is a technological marvel that becomes a financial liability when the engine self-destructs—which it does with alarming regularity due to catastrophic bearing and piston failures, often before 80,000 miles.
M279 V12 Catastrophic Engine Failure (Bearing/Piston Failure)
Common · high severityTypical onset: 40,000-80,000 mi
Symptoms: Sudden metallic knocking or rattling from engine bay, Loss of power, oil pressure warning light, Metal shavings in oil, visible on magnetic drain plug, Rough idle, misfires on multiple cylinders, Complete engine seizure in worst cases
Fix: This is the death knell. Connecting rod bearings and main bearings fail prematurely, leading to scored crankshafts and destroyed pistons. Only real fix is engine replacement or full rebuild with updated bearings (if crankshaft is salvageable). Rebuild: 60-80 hours labor. Replacement with used engine: 40-50 hours. Mercedes corporate has done goodwill cases on some low-mileage failures, but it's hit-or-miss.
Estimated cost: $35,000-65,000
Transmission Oil Cooler Leaks
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: Transmission fluid leaking from front of transmission, Pink/red fluid puddles under vehicle, Burnt transmission fluid smell, Slipping or delayed shifts if fluid gets low
Fix: The 7G-Tronic transmission oil cooler develops external leaks at the sealing surfaces. Requires cooler replacement and fresh ATF fill. Front subframe may need to be dropped for access. 6-9 hours labor depending on shop familiarity.
Estimated cost: $1,800-3,200
Transmission Mounts Collapsing
Occasional · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Clunking when shifting from Park to Drive or Reverse, Excessive vibration at idle in Drive, Visible sagging of transmission when inspected on lift, Harsh engagement into gear
Fix: The hydraulic transmission mounts fail and collapse, allowing excessive movement. Requires transmission support and mount replacement. Often do both mounts while in there. 4-6 hours labor.
Estimated cost: $1,200-2,200
Turbocharger Wastegate Rattle and Failure
Occasional · high severityTypical onset: 70,000-110,000 mi
Symptoms: Rattling noise on cold start that disappears after warmup, Loss of boost pressure, reduced power, Check engine light with underboost codes (P0299, P0234), Excessive black smoke under acceleration, Turbo whine or squealing
Fix: The wastegate actuators stick or the turbos themselves fail. V12 has two turbos nestled deep in the valley. Extremely labor-intensive—requires significant disassembly including intake manifolds, coolant lines, and exhaust components. 18-24 hours labor per side. Many shops won't touch this job.
Estimated cost: $8,000-14,000
ABC Active Body Control Suspension Leaks and Pump Failure
Common · medium severityTypical onset: 60,000-120,000 mi
Symptoms: Vehicle sitting low on one corner after sitting overnight, ABC warning light and message on dash, Whining or groaning from suspension pump, Fluid leaks at struts or hydraulic lines, Harsh ride, loss of active suspension functions
Fix: The Active Body Control system uses high-pressure hydraulic fluid that leaks from aging struts, accumulators, or lines. Pump failures also common. Strut replacement: 4-6 hours per corner. Pump: 5-7 hours. System must be bled and calibrated with STAR diagnostic system. Fluid is expensive proprietary ABC fluid.
Estimated cost: $3,500-8,000
Airmatic Compressor and Air Spring Failures
Occasional · medium severityTypical onset: 70,000-110,000 mi
Symptoms: Compressor runs constantly even when parked, Vehicle sags to bump stops overnight, Airmatic warning message on startup, Compressor clicking or grinding noises, Uneven ride height side-to-side
Fix: Air springs crack and leak, compressor overworks and burns out. Air springs: 2-3 hours each. Compressor: 3-4 hours. Often need to replace multiple components at once. System relearn required after repairs.
Estimated cost: $2,000-4,500
Pre-Safe Seatbelt Pretensioner Malfunction
Occasional · medium severitySymptoms: Pre-Safe malfunction warning on dash, Seatbelt warning light illuminated, Seatbelts may not retract properly, Related to NHTSA recall for premature deployment
Fix: Pretensioners fire prematurely or fault out. Covered under recall for some VINs. If not recall-eligible, requires seatbelt buckle/pretensioner assembly replacement. 2-3 hours per seat. Must be coded to vehicle.
Estimated cost: $800-1,500
Absolutely not—unless you have a spare $50k for an engine replacement and enjoy the thrill of uncertainty, avoid this V12 time bomb; the V8 S-Class models are infinitely more reliable.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.