2014 MERCEDES-BENZ E400 W212

Typical onset: 60,000-120,000 mi

Symptoms: Metallic rattling or knocking from engine at cold start that may disappear when warm, Check engine light with camshaft position sensor codes (P0016, P0017, P0018), Metal shavings in oil during changes, Sudden loss of power or complete engine seizure in severe cases

Fix: M276 balance shaft bearings wear prematurely, sending metal debris through the oil system and scoring cylinder walls, damaging pistons, rods, and bearings. By the time symptoms appear, contamination is widespread. Requires complete engine rebuild or replacement. 40-60 hours labor for rebuild, 25-35 hours for used engine swap.

Estimated cost: $12,000-22,000

Typical onset: 70,000-110,000 mi

Symptoms: Transmission fluid leaking from front of vehicle near radiator, Pink or red fluid puddles under car, Transmission overheating warnings, Harsh shifting or slipping if fluid level drops significantly

Fix: The plastic end tanks on the transmission oil cooler lines crack and leak. This is a known weak point on 722.9 transmissions. Must replace cooler lines and often the main radiator-mounted cooler assembly. Requires transmission fluid flush after repair. 4-6 hours labor.

Estimated cost: $800-1,400

Typical onset: 60,000-100,000 mi

Symptoms: Clunking when shifting from Park to Drive or Reverse, Vibration through floorboard at idle in gear, Excessive driveline movement visible when accelerating hard, Rougher shift feel overall

Fix: The hydraulic transmission mount deteriorates and leaks fluid, losing its damping ability. Common wear item on all W212s. Replacement requires supporting transmission and removing crossmember. 2-3 hours labor.

Estimated cost: $400-700

Typical onset: 80,000-130,000 mi

Symptoms: Rough idle and misfires, Oil consumption increase, Oil leaks from valve cover or rear main seal area, Check engine light with multiple misfire codes, Whistling or hissing from engine

Fix: The PCV system clogs with oil sludge, creating crankcase pressure that blows out seals and causes running issues. Valve is integrated into valve cover on driver side. Requires valve cover replacement and often spark plug replacement due to oil fouling. 4-5 hours labor.

Estimated cost: $1,200-1,800

Typical onset: 50,000-90,000 mi

Symptoms: Strong fuel smell in cabin or near vehicle, Visible fuel wetness on top of engine passenger side, Check engine light with fuel system lean codes, Rough running or hesitation on acceleration

Fix: The plastic fuel filter housing develops cracks, typically at the seams or mounting points. Located under intake manifold, so access requires removing airbox and sometimes loosening manifold. Filter service often reveals cracked housing. 3-4 hours labor.

Estimated cost: $600-1,000

Typical onset: 70,000-120,000 mi

Symptoms: Vehicle sitting low on one or both ends after sitting overnight, Airmatic warning on dash, Compressor running excessively (audible whirring from rear), Uneven ride height side-to-side

Fix: Air struts develop leaks at the rubber bellows or piston seals. Compressor overworks trying to maintain pressure and fails prematurely if ignored. Must replace struts in pairs per axle. 3-4 hours per axle. Note: Not all E400s have Airmatic, but it's common on this trim.

Estimated cost: $2,000-3,500