2017 MERCEDES-BENZ E450 W213

Typical onset: 30,000-70,000 mi

Symptoms: Sudden knocking or ticking from engine bay, Low oil pressure warning, Metal shavings in oil, Catastrophic engine failure with no prior warning

Fix: This is the nuclear option: either short block replacement (16-20 hours) or full engine rebuild with new bearings, pistons, and rings (25-35 hours). Mercedes issued a TSB and extended warranty coverage for some VINs, but many 2017s fall outside that window now. Always check oil consumption history before buying.

Estimated cost: $15,000-25,000

Typical onset: 60,000-90,000 mi

Symptoms: Red transmission fluid pooling under vehicle, Transmission overheating warning, Delayed or harsh shifts when hot, Burnt smell from transmission

Fix: The 9G-TRONIC cooler develops pinhole leaks at the crimped seams. Replacement is straightforward: drain trans fluid, drop cooler lines, replace cooler and seals. Takes about 3-4 hours. Flush and refill with MB-approved ATF (9 liters). Don't ignore this—running low on fluid kills the transmission.

Estimated cost: $800-1,400

Typical onset: 70,000-100,000 mi

Symptoms: Clunk or thud on acceleration or deceleration, Vibration at idle that worsens with AC on, Excessive engine movement visible when revving in Park, Transmission slap when shifting into Drive or Reverse

Fix: The hydraulic engine mounts and rear transmission mount fail on schedule. Fronts take 2 hours each, rear trans mount about 1.5 hours. Use OEM or Lemförder—aftermarket rubber mounts don't last. This is a comfort issue until it becomes a drivability issue. Replace all three at once if you're over 80k.

Estimated cost: $1,200-2,000

Typical onset: 50,000-80,000 mi

Symptoms: Hard start after sitting overnight, Fuel smell near passenger side of engine, Extended cranking before engine fires, P0087 low fuel pressure code

Fix: The inline fuel filter housing develops cracks or O-ring leaks, causing fuel to seep and air to enter the system. Filter lives under the intake manifold—access is tight. Plan 3-4 hours to remove intake, replace filter housing and seals, bleed system, reassemble. Use genuine MB parts; aftermarket filters don't seal right.

Estimated cost: $600-1,100

Typical onset: 40,000-70,000 mi

Symptoms: Rough idle or stumbling at low RPM, Check engine light with P0171/P0174 lean codes, Oil consumption increase, Whistling or hissing noise from engine bay

Fix: The M256's integrated oil separator valve clogs with carbon buildup, causing vacuum leaks and lean running. Replacement involves removing the valve cover (2.5-3 hours). Clean the intake ports while you're in there. This is maintenance, not optional—ignoring it stresses the turbo seals and increases oil consumption.

Estimated cost: $700-1,200

Typical onset: 80,000-120,000 mi

Symptoms: Vehicle sits low on one corner after sitting overnight, Compressor runs constantly or cycles frequently, Suspension warning on dash, Harsh ride quality or bottoming out

Fix: If equipped with AIRMATIC, expect the compressor or a strut to fail eventually. Compressor replacement is 2-3 hours; a single strut is 2 hours. Rebuilt compressors are available and reliable. Budget for all four struts if you're over 100k—they leak internally and can't be rebuilt cost-effectively. Coilover conversion kits exist but affect resale.

Estimated cost: $1,500-3,500