2017 MERCEDES-BENZ S450 W222

Typical onset: 40,000-80,000 mi

Symptoms: Loud rattling or knocking noise from engine bay, especially on cold start, Metal shavings in oil during oil change, Check engine light with timing correlation codes (P0016, P0017, P0018), Sudden loss of power or complete engine seizure

Fix: The M276 engine has a known defect where the balance shaft gear wears prematurely and disintegrates, sending metal debris throughout the engine. This destroys bearings, scores cylinder walls, and clogs oil passages. Requires complete engine rebuild or replacement. Labor alone is 30-40 hours for rebuild, 20-25 hours for long block swap. Mercedes issued extended warranty coverage (KB 2017050006) but many 2017s fall outside it.

Estimated cost: $15,000-25,000

Typical onset: 50,000-90,000 mi

Symptoms: Red ATF puddles under vehicle, typically passenger side, Transmission temperature warning on dash, Burnt transmission fluid smell, Sluggish shifting or limp mode if fluid level drops significantly

Fix: The cooler lines running to the radiator develop leaks at crimp points and connectors. Often the entire cooler assembly needs replacement, not just lines. Requires front bumper removal for access. 4-6 hours labor plus fluid refill and adaptation procedures.

Estimated cost: $1,200-2,200

Typical onset: 60,000-100,000 mi

Symptoms: Clunking noise when shifting from Park to Drive or Reverse, Excessive vibration at idle in Drive, Visible sagging or torn rubber on mount during inspection

Fix: The hydraulic transmission mount collapses internally, allowing excessive powertrain movement. Replacement is straightforward but requires supporting the transmission. 2-3 hours labor. OEM mount strongly recommended over aftermarket.

Estimated cost: $600-1,000

Symptoms: Extended cranking before starting, Rough idle and misfires, Loss of power under acceleration, Multiple cylinder misfire codes

Fix: The in-tank fuel filter clogs prematurely, especially if balance shaft failure occurred and metal contaminated the fuel system during catastrophic failure. Filter is part of the fuel pump module. Tank must be dropped. If contamination is severe, injectors need cleaning or replacement. 5-7 hours for pump module, add 8-10 hours if injectors need service.

Estimated cost: $1,500-4,500

Typical onset: 70,000-110,000 mi

Symptoms: Vehicle sits low, especially after sitting overnight, Airmatic suspension warning on dash, Compressor runs excessively or constantly, Uneven ride height side-to-side

Fix: Airmatic struts develop leaks at seals, and the compressor wears out from overwork. Each strut is 3-4 hours, compressor is 4-5 hours. Front struts fail more often than rears. Many owners convert to coil springs ($2,500-3,500) rather than replace with air struts long-term.

Estimated cost: $2,000-3,500 per strut, $2,500-3,500 for compressor

Typical onset: 50,000-90,000 mi

Symptoms: Deep knocking noise that increases with RPM, Low oil pressure warning, Metal particles visible in oil filter during inspection, Engine noise worse when warm

Fix: Even if balance shaft failure is caught early, metal debris often circulates through bearings causing accelerated wear. Requires engine removal, complete disassembly, crankshaft inspection/machining, and new bearings throughout. 35-45 hours labor. Often more economical to replace with used engine or remanufactured long block.

Estimated cost: $12,000-20,000