Mercedes-Benz S 350
Four-valve V6 with variable valve timing. Smooth and powerful. Known for balance shaft wear (revision sprocket) on early build years. Balance shaft gear problem addressed by Mercedes with a recall.
Solid Basis
200 kW — everyday-capable power, without excitement.
Engine Weaknesses 6
The plastic balance shaft sprocket on the M272 wears prematurely from the timing chain. The right cylinder bank goes out of timing. Affected up to end of October 2006.
Symptoms: Fault codes P0016/P0017 (camshaft right bank), chain rattling, rough running at idle, in extreme cases engine damage
Alongside the balance shaft issue the M272 shows premature timing chain stretch. Chain wear on softer sprockets leads to timing deviations.
Symptoms: Chain noise especially on cold start, camshaft fault codes, rough running, engine irregularities
Four camshaft adjuster solenoids (two per cylinder bank) develop leaks; oil creeps into the wiring harness as far as the ECU. Repair costs up to €1,700 documented.
Symptoms: CEL, oil traces at camshaft connectors, lambda sensor failure due to oil contamination, non-specific faults that recur
Plastic components of the M272 variable intake system become brittle and break. The intake flap linkage snaps and sets fault code P2006.
Symptoms: Fault codes P2004/P2005/P2006 (intake flap), slight power loss, check engine light
The thermostat on the M272 preferentially fails in the open position. Operating temperature is not reached; especially on motorway runs temperature drops to 75–80°C.
Symptoms: Engine doesn't reach 90°C after 10–20 km, coolant temperature fluctuates heavily, reduced heater output, fault code P0128
The hydraulic engine mounts on the M272 lose their damping effect with age. Jerky movements are especially apparent when lifting off the throttle and during gear changes.
Symptoms: Vibrations in steering wheel and gear lever during load changes, judder on gear changes, droning at low revs
Vehicle Weaknesses 6
The air struts of the W221 wear over time. Between 200,000 and 300,000 km, all four struts typically need replacement.
The Airmatic pressure reservoir tanks at the rear axle can corrode. Removal requires disassembly of the rear axle.
The instrument cluster develops pixel faults due to detached ribbon cables. In worst case, complete display failure.
The W221 shows sporadic CAN bus communication faults leading to failures of various systems: ESP, headlight control, fog lights.
Air spring bags (usually rear) become leaky and lose pressure gradually. The vehicle then sits 3–4 cm lower on one side. Fault code 5285 (fill process too long) appears. Repair is only possible by replacement.
The W221's extensive comfort electronics are fault-prone: electric windows, door mirrors and the optional panoramic sunroof show failures due to aged connectors and control units.
Reports & Tests
233 owner complaints filed with NHTSA (2005–2013). Most reported: Electrical (63), Engine (41), Powertrain (35).