The W220 S320 CDI with the OM613 engine is a complex luxury diesel that suffers from catastrophic engine failures due to biodiesel-related injector fouling and oil sludging, plus typical W220 airmatic and electrical gremlins. When the engine goes, it's often a total-loss scenario.
Symptoms: Excessive black smoke on startup or acceleration, Sudden loss of power followed by severe knocking, Metal shavings in oil, low oil pressure warning, Seized engine or rod through block in worst cases
Fix: The OM613 is infamous for injector tip carbon buildup that breaks off, scores cylinders, and destroys bearings. Biodiesel accelerates this. Fix requires engine-out rebuild or short block replacement: 25-35 hours labor plus machine work. Many shops won't touch it—recommend reman long block.
Estimated cost: $8,000-15,000
Oil Sludging and Camshaft Wear
Common · high severity
Typical onset: 60,000-120,000 mi
Symptoms: Valve train noise, especially cold start ticking, Low oil pressure at idle when hot, Check engine light with camshaft position codes, Oil starvation damage to head components
Fix: Extended service intervals and wrong-spec oil cause sludge in the head. Cam lobes wear, followers collapse. Head removal, cleaning, cam replacement, and new followers: 18-24 hours. Often found during diagnosis for other engine issues.
Estimated cost: $4,500-7,500
Airmatic Suspension Failures
Common · medium severity
Typical onset: 70,000-130,000 mi
Symptoms: Vehicle sagging on one or both corners overnight, Airmatic warning light with 'Visit Workshop' message, Compressor runs constantly or won't run at all, Harsh ride or excessive body roll
Fix: Air struts leak at 100k-ish, compressor valve blocks fail, level sensors corrode. Each strut: 2-3 hours. Compressor: 3-4 hours. Full system overhaul (all four struts + compressor): 12-15 hours. Many convert to coils for $1,500-2,500.
Estimated cost: $800-1,200 per strut, $1,800-2,800 compressor, $4,500-6,500 all four corners
Transmission Conductor Plate and Valve Body Issues
Occasional · high severity
Typical onset: 90,000-150,000 mi
Symptoms: Harsh or delayed shifts, especially 2-3 and 3-4, Limp mode with P0715 or P0700 codes, Slipping under load or no movement in gear, Transmission fluid overheating
Fix: The 722.6 transmission's 13-pin conductor plate cracks solder joints; valve body solenoids stick. Pan drop, valve body R&R, new conductor plate and fluid: 8-10 hours. If clutches are burnt from slipping, add rebuild: 18-22 hours total.
Estimated cost: $1,800-3,200 conductor plate/valve body, $4,500-6,500 full rebuild
SBC (Sensotronic Brake Control) Pump Failure
Occasional · high severity
Typical onset: 80,000-140,000 mi
Symptoms: Red 'BRAKE VISIT WORKSHOP' warning with gong, Hard brake pedal or complete loss of power assist, ABS/ESP lights on, traction control disabled, Whining or buzzing from under hood near firewall
Fix: The hydraulic brake-by-wire pump fails (motor or accumulator). Mercedes discontinued new units; reman/exchange only. Remove and replace pump: 4-6 hours. Must be coded to car. This is a known W220 ticking time bomb.
Estimated cost: $2,500-4,000
Fuel Injection System (Injectors and High-Pressure Pump)
Occasional · high severity
Typical onset: 100,000-180,000 mi
Symptoms: Hard starting, long cranking, white smoke, Rough idle, misfires on one or more cylinders, Poor fuel economy, loss of power under load, Metal contamination in fuel filter
Fix: Bosch common-rail injectors seize or leak internally; high-pressure pump cam wears. Injectors: 6-8 hours for all six (must remove intake). HP pump: 5-7 hours. If metal in system, flush rails and replace all injectors plus pump.
Estimated cost: $3,500-5,500 injectors, $1,800-2,800 HP pump, $6,000-9,000 full system
ABC (Active Body Control) Hydraulic Leaks
Occasional · medium severity
Typical onset: 80,000-140,000 mi
Symptoms: ABC warning light, 'Car Too Low' message, Green hydraulic fluid puddles under car, Harsh ride, clunking over bumps, Pump running excessively, whining noise
Fix: If equipped with ABC (some S320 CDI have airmatic instead), hoses, accumulators, and pulsation dampeners leak. Each front strut: 4-5 hours. Rear: 3-4 hours. Pump: 6-8 hours. This system is a money pit; budget $10k+ for full repair.
Estimated cost: $1,200-2,000 per strut, $2,500-4,000 pump, easily $8,000-12,000 for comprehensive repair
Owner tips
Use only MB-approved 229.51 diesel oil (5W-30) and change every 5,000 mi maximum—OM613 sludges badly with longer intervals
Avoid biodiesel blends above B5; they accelerate injector carbon buildup and fuel system failures
Budget $2,000/year minimum for suspension and brake system repairs—W220 hydraulics are maintenance nightmares
Get a pre-purchase inspection with borescope check of cylinders and oil analysis—many OM613s are ticking time bombs by 100k
Keep detailed service records; these cars punish deferred maintenance harder than any other Mercedes
Hard pass unless you're a diesel specialist with a lift and deep pockets—the OM613 engine failures alone make this a financial trap, and W220 complexity multiplies the pain.
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.
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Fitment notes: Located in trunk on right side; AGM battery required for vehicle electronics; higher capacity recommended for diesel engine
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Every control module on the 2000-2006 Mercedes-Benz S320 CDI W220 — 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.
⚠️ Controls power seat, memory, heating; basic coding for seat type. Two modules (left/right).
Bi-Xenon Control Unit (XCU)0.5 hr R&Rrelearn only +0.2 hr▸ programming details
📍 Behind each headlight assembly
🔧 Star Diagnosis
⚠️ Xenon headlight ballast/controller; auto-leveling calibration required. Two modules (left/right). Not all S320 CDI have xenon.
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 2004 Mercedes-Benz S320 CDI W220 3.2L I6 Diesel OM613 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.