The 2016 S600 with the M279 6.0L twin-turbo V12 is a technological flagship with catastrophic engine failure potential that overshadows every other concern. When the engine is healthy, you're chasing ABC suspension leaks and electrical gremlins, but the piston-cracking issue makes this a high-stakes gamble.
Catastrophic Engine Failure - Piston Cracking and Bearing Damage (M279 V12)
Occasional · high severityTypical onset: 30,000-70,000 mi
Symptoms: Sudden onset of severe misfires, often multiple cylinders, Metallic knocking or rattling from engine block, Check engine light with misfire codes P0300-P030C, Coolant loss with no external leaks, Catastrophic failure: rod through block, seized engine
Fix: This is the M279's Achilles heel: piston skirt cracking leads to ring land failure, then bearing contamination from aluminum debris. Mercedes issued service campaigns but no full recall. Repair requires complete engine rebuild (pistons, rings, bearings, machine work, reassembly) at 80-120 labor hours, or shortblock replacement at 60-80 hours. Many owners opt for used engine swaps. Zero DIY viability.
Estimated cost: $35,000-65,000
Active Body Control (ABC) Suspension System Failures
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: ABC warning light and 'ABC malfunction' message, Car drops to bump stops when parked or driving, Hydraulic fluid leaks visible under struts or accumulator, Harsh ride or uneven stance, Hissing noise from hydraulic pump
Fix: The ABC system uses hydraulic struts prone to internal seal failure. Each corner strut runs $2,500-3,500 for genuine parts, 3-4 hours labor per corner. Pulsation dampers fail ($800-1,200 each, 2-3 hours), and the tandem pump can seize ($4,000-5,000 parts, 8-10 hours). Budget $1,500-2,000 for fluid flush and filter annually as preventive.
Estimated cost: $3,000-8,000
Transmission Oil Cooler Leaks (722.9 Seven-Speed)
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: Transmission fluid visible on garage floor, pink/red color, Cooler lines seeping at crimped connections, Transmission overheating warnings in heavy use, Fluid level dropping between services
Fix: The external oil cooler develops pinhole leaks or crimped line failures. Replacement requires new cooler assembly, lines, and 13-conductor connector housing that cracks ($1,200-1,800 parts). 4-6 hours labor including refill and adaptation with XENTRY. Ignoring this leads to torque converter or valve body damage from low fluid.
Estimated cost: $2,000-3,500
Transmission Mounts Collapsing
Common · low severityTypical onset: 40,000-80,000 mi
Symptoms: Clunk or thud on hard acceleration or deceleration, Vibration through floorboard at idle in Drive, Excessive driveline movement visible on lift, Transmission 'hunting' between gears under light throttle
Fix: The hydraulic transmission mount deteriorates from heat and weight of the 722.9. OEM mount is $400-600, 2-3 hours labor to drop subframe bolts and swap. Cheap aftermarket mounts fail in 10,000 miles. Often done alongside engine mounts as a set.
Estimated cost: $800-1,500
Airmatic Air Suspension Component Failures (If Not ABC-Equipped)
Occasional · medium severityTypical onset: 70,000-110,000 mi
Symptoms: Airmatic warning on dash, Vehicle sagging at one corner overnight, Compressor running excessively, Harsh ride or bouncing over bumps
Fix: Note: Most S600s have ABC, but some markets got Airmatic. Air struts fail at diaphragm ($1,500-2,200 each, 2-3 hours). Compressor relay failures cause no-start of pump ($200-400, 1 hour). Valve block internally leaks ($2,000-3,000, 4-5 hours). Less catastrophic than ABC but still $$$.
Estimated cost: $2,000-4,500
COMAND Infotainment and Fiber Optic Network Faults
Occasional · low severitySymptoms: COMAND screen freezes or reboots randomly, Loss of audio, navigation, or phone functions, Multiple control modules showing 'no communication' on scan, Instrument cluster going dark intermittently, Battery drain from modules staying awake
Fix: The MOST fiber optic ring is fragile. Connectors at gateway module or COMAND head unit corrode (1-2 hours diagnosis, $150-400 parts for connectors/fiber loops). Head unit failures require coding and used-unit adaptation (6-8 hours with software, $2,000-3,500 for reman unit). Parasitic draw testing takes 2-4 hours to isolate sleeping module failures.
Estimated cost: $500-4,000
Buy only with a comprehensive pre-purchase inspection including borescope and ABC pressure test, or budget $50K in escrow for engine replacement — the M279 piston issue is a ticking time bomb that makes even cheap examples expensive.
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.