Mercedes-Benz S 600
Twelve cylinders, two turbochargers, a V-valley layout — technically fascinating and maintenance-intensive in equal measure. The fully encapsulated ignition module system with two banks at 1,400 EUR each is the most well-known cost factor; failure of both banks usually follows in quick succession. The oil-water heat exchanger in the V-valley almost always leaks eventually — factor in engine removal for the repair. The four camshaft solenoids fail to seal reliably after 80,000–100,000 km; oil creeps into the wiring harness and corrodes control units. Both turbochargers sit deep under the engine bay — removal and installation costs more than the turbo itself. Runs without issue beyond 300,000 km with diligent maintenance; what kills it is deferred servicing. Purchase requirement: complete service history, documented wiring harness check, no ABC alarm backlog, fresh ignition modules.
S 600 W222 — The Last V12 Saloon from Stuttgart
390 kW V12 BiTurbo in the W222: more power than ever, more refinement than ever. The improvement over the W221 is in the details — quieter, more composed, even more effortless. Magic Body Control makes even this power level feel like a non-event. The last great S600: production ended in 2019. Collector status already secured.
Engine Weaknesses 9
Both ignition module banks are fully potted wear items with a typical service life of 10–15 years. Failures tend to follow each other quickly. OEM cost approximately €1,400 each.
Symptoms: Jerking and power loss, rough running, misfire codes P0307–P0312, petrol smell from the exhaust
The two turbochargers show bearing and wastegate wear at high mileage. Engine removal is required for replacement; repair costs €2,000–4,000 per turbo.
Symptoms: Whistling or rattling turbo noises, power loss under hard acceleration, blue smoke from oil loss
The M275 V12 Biturbo in the S600/CL600 puts extreme stress on the engine mounts due to its weight (>300 kg engine). At the same time, the ABC hydraulic lines age and leak. Both issues frequently occur together.
Symptoms: ABC suspension hydraulic oil loss, engine sitting lower, vibrations in the cabin, ABC warning message
On the M275 V12 with 4 camshafts, all 4 solenoids are affected. Oil leaking into the wiring harness leads to ECU corrosion. Repair is especially labour-intensive on the V12.
Symptoms: Cold-start rattle, camshaft adjuster fault codes bank 1+2, oil traces on connectors, in extreme cases engine ECU failure
Wiring harness insulation in the engine bay becomes brittle after 10–15 years from heat. Affected: injector, MAF and throttle body wiring. Short circuits in the MAF harness can destroy the engine beyond repair.
Symptoms: Sporadic misfires, MAF fault codes, ignition misfires without clear cause, in extreme cases engine failure and fire risk.
The integrated contact plate (TCM) in the 7G-Tronic fails due to heat damage at the speed sensors. Gearbox shifts jerkily, then not at all. New plate requires SCN coding at an authorised dealer.
Symptoms: Delayed, jerky gear changes, gearbox stuck in 2nd gear (limp mode), fault codes P0717/P0718 transmission control unit.
The oil-water heat exchanger seal in the V-valley becomes leaky. Engine removal is required for repair, so total costs reach €1,700–2,500 despite the cheap parts.
Symptoms: Oil loss without a clearly visible leak, oil spots after extended parking, occasionally oil in the coolant reservoir
The separate intercooler cooling circuit loses coolant through ageing hoses and O-rings. Retrofit fix: the M279 expansion tank fits as a direct swap.
Symptoms: Dropping coolant level in the expansion tank, overheating warning on extended motorway runs, power reduction
Valve stem seals harden and piston rings wear with increasing mileage. 12 cylinders mean 48 valve stem seals. Oil consumption rises noticeably from 150,000 km — up to 1 L/2,000 km.
Symptoms: Blue smoke after prolonged idle, dropping oil level between service intervals, carbon deposits on spark plugs.
Vehicle Weaknesses 14
The active electro-hydraulic ABC suspension requires intensive maintenance. Hydraulic lines, valve blocks and pumps can develop leaks. Hydraulic oil change required every 50,000 km.
Air bags and pressure hoses develop leaks. The compressor runs continuously and overheats. Repair: air bag pair 2,500–3,500 €, compressor 1,000–1,300 €.
Air struts on Airmatic and Magic Body Control suspensions develop leaks. Vehicle drops, suspension warning light appears. Repair per corner is very costly.
The hydraulic Magic Body Control suspension is prone to valve block and hydraulic pump failures. Contamination in the oil causes system failures.
The COMAND infotainment system freezes sporadically or fails completely. System faults increase from around 100,000 km.
Radar and camera sensors for adaptive cruise control and emergency braking can cause malfunctions due to dirt or defects. Calibration after repair is expensive.
The COMAND navigation system shows read errors, freezes or fails to boot. A defective drive unit is the most common cause.
Matrix LED headlights are not repairable -- individual modules cannot be replaced. Moisture and electronic failures require complete headlight replacement.
Window regulators fail or become unresponsive. Cause is often a software fault in the door control unit, fixable by update.
Brake discs and pads wear quickly due to the high vehicle weight. Particularly during spirited driving.
The pneumatic control unit operates soft-close, central locking and rear headrests via a shared pump. Leaks cause all functions to fail simultaneously.
The Comand NTG5 infotainment system shows display failures, freezing and navigation start errors. Temperature-dependent malfunctions occur frequently.
Seat heating mats and massage pneumatics in the multicontour seats are wear items. Heating mats fail internally, the PSE pump loses pressure for the massage function.
The rubber seal of the Keyless Go microswitch in door handles becomes brittle through UV and temperature cycling. Moisture enters, the switch corrodes.