The 2017 E450 W213 with the M256 3.0L inline-6 turbo is a solid platform, but the first-gen M256 engine had catastrophic oiling issues affecting early production units. When it fails, it's expensive and total. Transmission cooler leaks and motor mount failures are common wear items that hit around 60-80k miles.
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
Transmission Oil Cooler Leak
Common · medium severity
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
Engine Mount / Transmission Mount Deterioration
Common · low severity
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
Fuel Filter Housing Leak / Fuel System Pressure Loss
Occasional · medium severity
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
Crankcase Ventilation Valve / PCV System Clogging
Common · low severity
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
AIRMATIC Air Suspension Compressor / Strut Failure
Occasional · medium severity
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
Owner tips
Check service history for oil consumption monitoring—MB tracked this on early M256s. Walk away if records are missing.
Change transmission fluid every 40-50k miles despite MB claiming 'lifetime' fill. The 9G-TRONIC rewards preventive care.
Use 0W-40 MB 229.5 oil and keep the interval at 7,500 miles max. This engine is sensitive to oil quality and level.
Inspect engine mounts at every oil change after 60k—catching them early prevents harsh shifts and drivetrain stress.
If buying used, budget $2-3k for deferred maintenance (mounts, trans cooler, PCV valve) on anything over 60k miles.
Buy a 2018+ model year if possible—the early M256 oiling problems were largely resolved after mid-2017 production, and you'll sleep better. Otherwise, verify extended warranty coverage or plan for a potential engine replacement fund.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: AGM required for start-stop system; battery located in engine compartment; additional auxiliary battery in trunk
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Every control module on the 2017 Mercedes-Benz E450 W213 — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Transmission Control Unit (TCU)3.5 hr R&Rdealer / factory tool +1.0 hr▸ programming details
📍 Transmission housing, driver side near valve body
🔧 Xentry Diagnostics + SCN coding
⚠️ Requires transmission fluid drain and valve body removal. VIN-locked, SCN coding mandatory.
Electric Power Steering Control Unit (EPS)2.5 hr R&Rdealer / factory tool +1.0 hr▸ programming details
📍 Steering column, integrated with steering gear
🔧 Xentry Diagnostics + SCN coding
⚠️ Requires steering angle sensor calibration and road test. VIN-locked.
4MATIC Control Unit (4M)2.0 hr R&Rdealer / factory tool +1.0 hr▸ programming details
📍 Transmission tunnel, near transfer case (4MATIC models only)
🔧 Xentry Diagnostics + SCN coding
⚠️ Only on 4MATIC AWD models. Requires drivetrain adaptation and road test. VIN-locked.
Signal Acquisition and Actuation Module - Front (SAM-F)1.8 hr R&Rdealer / factory tool +1.5 hr▸ programming details
📍 Engine compartment, left side fuse box
🔧 Xentry Diagnostics + SCN coding
⚠️ Controls most front electrical functions. Replacement requires extensive coding of all connected systems. VIN-locked.
Electronic Stability Program Control Unit (ESP/ABS)1.5 hr R&Rdealer / factory tool +0.8 hr▸ programming details
📍 Engine compartment, left front near fender
🔧 Xentry Diagnostics + SCN coding
⚠️ Integrated hydraulic unit. Brake bleeding required after replacement. VIN-locked.
⚠️ Seat position memory adaptation required. Not heavily VIN-locked, aftermarket tools often work.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2017 Mercedes-Benz E450 W213 3.0L I6 Turbo M256 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.