The 2009 S600 with the M275 5.5L twin-turbo V12 is a magnificent highway cruiser when healthy, but this engine is catastrophically failure-prone due to fundamental design flaws in the crankshaft and bearing tolerances that often require complete rebuilds between 60,000-100,000 miles.
M275 Engine Bearing Failure and Crankshaft Wear
Common · high severity
Typical onset: 60,000-100,000 mi
Symptoms: Metallic knocking or ticking from lower engine, Oil pressure warning at idle when warm, Metal shavings or glitter in oil during changes, Rough idle and power loss, Eventually catastrophic rod knock and engine seizure
Fix: The M275 suffers from undersized main and rod bearings combined with crankshaft flex under boost. Fix requires engine removal, complete disassembly, crankshaft machining or replacement, all new bearings, typically pistons and rings while you're in there. 60-80 hours labor for full rebuild, 40-50 for short block swap if you source a good used unit.
Estimated cost: $15,000-30,000
Turbocharger Failure
Occasional · high severity
Typical onset: 80,000-120,000 mi
Symptoms: Blue smoke on startup or acceleration, Screaming or grinding noise under boost, Sudden loss of power, Check engine light with underboost codes, Oil consumption increase
Fix: Turbos fail from oil starvation (often related to the bearing problems) or shaft wear. Requires removing engine undertray, exhaust components, and turbo assemblies. 12-16 hours per side, always do both if one fails. Must address root cause oil pressure issues or new turbos will fail quickly.
Estimated cost: $8,000-14,000
Transmission Oil Cooler and Conductor Plate Failure
Common · medium severity
Typical onset: 70,000-110,000 mi
Symptoms: Harsh or delayed shifts, Transmission slipping between gears, Limp mode activation, Transmission overheating warnings, Fluid leaks from bell housing area or cooler lines
Fix: The 722.9 seven-speed has issues with internal oil cooler and valve body conductor plate. Cooler lines crack, conductor plate wiring harness fails. Requires transmission removal for proper repair. 18-24 hours labor including fluid flush and adaptations.
Estimated cost: $4,500-7,500
ABC Active Body Control Hydraulic System Leaks
Common · medium severity
Typical onset: 80,000-130,000 mi
Symptoms: Suspension warning light, Car sitting low on one corner, Hydraulic fluid puddles under car, Rough ride quality, ABC inactive message, Whining noise from pump
Fix: ABC struts, accumulators, and hydraulic lines develop leaks. Strut replacement is 3-5 hours per corner. Pump replacement is 6-8 hours. Lines vary. System uses expensive MB-specific fluid. Must pressure test to find all leaks as one repair often reveals another.
Estimated cost: $2,500-8,000
Airmatic Air Suspension Compressor and Strut Failure
Occasional · medium severity
Typical onset: 90,000-140,000 mi
Symptoms: Compressor runs constantly, Car sagging overnight or when parked, Suspension warning light, Inability to raise or lower suspension, Compressor overheating and shutting down
Fix: If equipped with Airmatic instead of ABC, compressor and valve block fail from overwork due to strut leaks. Struts 3-4 hours each, compressor 4-6 hours. Always inspect all four struts when one fails. Relay and valve block issues add diagnostic time.
Estimated cost: $2,000-5,000
Fuel System Issues - High Pressure Pump and Injectors
Occasional · high severity
Typical onset: 100,000-150,000 mi
Symptoms: Extended cranking before start, Rough running and misfires, Fuel smell in cabin or engine bay, Check engine light with fuel trim codes, Loss of power under load
Fix: Direct injection system runs extremely high pressure. Pump fails, injectors leak or clog. Pump is 6-8 hours in the valley of the V12. Injectors are 10-14 hours for all twelve due to access. Fuel filters also commonly neglected on this chassis.
Estimated cost: $3,500-9,000
Engine and Transmission Mounts
Common · low severity
Typical onset: 60,000-100,000 mi
Symptoms: Clunk when shifting into drive or reverse, Vibration at idle in drive, Excessive engine movement visible when accelerating, Transmission thunk during shifts
Fix: Hydraulic mounts fail from age and the V12's weight. Engine mounts are 4-6 hours, transmission mount is 3-4 hours. Critical to replace before they damage other components. Relatively cheap compared to other S600 issues.
Estimated cost: $1,200-2,500
Owner tips
Change engine oil every 5,000 miles maximum with quality 0W-40 synthetic — the bearing clearances demand it and might buy you time
Have oil analysis done every oil change to watch for bearing material before catastrophic failure
Budget $3,000-5,000 annually for maintenance and repairs if buying used — this is not an affordable car to own
Find a specialist independent shop familiar with M275 engines — dealer rates will bankrupt you
Seriously consider an extended warranty if purchasing, but read the fine print on engine internal coverage
The transmission valve body should be serviced every 60k miles with fluid and filter regardless of 'lifetime' claims
Absolutely not unless you have a $20,000 emergency fund dedicated to this car — the M275 engine is a ticking time bomb that will almost certainly need a full rebuild, making this one of the least reliable luxury sedans ever made.
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.
Fitment notes: AGM battery required; located in trunk; high-performance V12 requires premium AGM battery with high CCA
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Every control module on the 2008-2013 Mercedes-Benz S600 — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Active Body Control (ABC)2.0 hr R&Rdealer / factory tool +0.8 hr▸ programming details
📍 Front passenger footwell, behind the carpet/kick panel
🔧 Xentry/DAS with SCN
⚠️ Hydraulic active suspension; pump and accumulator failures common; system bleed required after service · Location verified on same-chassis S65 (W221) by owner 2026-07-19 and propagated; engine-bay components are the ABC hydraulics, not the control unit.
Electronic Stability Program / Anti-lock Brake System (ESP/ABS)1.8 hr R&Rdealer / factory tool +0.8 hr▸ programming details
📍 Engine compartment, left front near fender
🔧 Xentry/DAS with SCN
⚠️ Sensotronic Brake Control (SBC) system through 2009 MY; notorious for pump failure; 2010+ conventional ESP
⚠️ Multi-contour massage seats; memory positions stored in module
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2009 Mercedes-Benz S600 5.5L V12 BiTurbo M275 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.