Mercedes-Benz · Known Issues
2021 Mercedes-Benz Sprinter Problems & Issues
2021 model year · 6,900+ owner reports · Updated September 2026
2021 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
2021 model year · 6,900+ owner reports · Updated September 2026
2021 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
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According to Au7o's analysis of 6,900+ owner reports, the 2021 Mercedes-Benz Sprinter has 12 documented known issues, with 5 rated critical. The most serious are Diesel Injector Failure and Black Death (OM651/OM654) ($300-$3,000 repair), DEF/AdBlue SCR System Faults and Derate ($500-$3,500 repair), Turbocharger VNT Actuator Failure (Boost Faults, Limp Mode) ($400-$1,500 repair), Front Lower Control Arm Ball Joint Wear (Radial Play, Inner Front Tire Wear) ($500-$1,600 repair) and OM642 V6 Oil Cooler Seal Leak (Oil in the Engine Valley) ($900-$2,000 repair). The most commonly reported issue is Diesel Injector Failure and Black Death (OM651/OM654) with 2,400 owner reports. Across all issues with published estimates, repair costs range from $150 to $3,500. DIY maintenance guides at au7o.io.
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According to Au7o's analysis of 6,900+ owner reports, the 2021 Mercedes-Benz Sprinter has 12 documented issues. The most frequently reported are: Diesel Injector Failure and Black Death (OM651/OM654), DEF/AdBlue SCR System Faults and Derate, Turbocharger VNT Actuator Failure (Boost Faults, Limp Mode). Of these, 5 are rated critical and should be addressed promptly.
The 2021 Mercedes-Benz Sprinter has 12 known issues documented across 6,900+ owner reports. 5 issues are rated critical: Diesel Injector Failure and Black Death (OM651/OM654) and DEF/AdBlue SCR System Faults and Derate and Turbocharger VNT Actuator Failure (Boost Faults, Limp Mode) and Front Lower Control Arm Ball Joint Wear (Radial Play, Inner Front Tire Wear) and OM642 V6 Oil Cooler Seal Leak (Oil in the Engine Valley). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
Repair costs for known Mercedes-Benz Sprinter issues range from $0 to $3,500, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Diesel Injector Failure and Black Death (OM651/OM654), typically costs $300-$3,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
Sprinter diesel injectors develop seal failures leading to the "Black Death" condition where combustion gases leak past the injector copper washers, carbonizing and creating hard tar deposits around the injector bore. This is the most common and feared Sprinter repair, as advance… Repairs typically run $300-$3,000. Severity: high.
The Sprinter diesel exhaust fluid (DEF/AdBlue) selective catalytic reduction system is plagued by faults in the dosing module, NOx sensors, DEF heater, and SCR catalyst. Failures trigger the dreaded "engine derate" countdown that limits vehicle speed to 5 mph if not resolved, str… Repairs typically run $500-$3,500. Severity: high.
Sprinter diesels use a variable-geometry turbo whose vane position is controlled by an electronic actuator (PWM-driven on the OM642; vacuum/wastegate-controlled on some OM651). The actuator's electronics or worm-drive wear out, so the ECU can no longer command correct boost. The… Repairs typically run $400-$1,500. Severity: high.
The Sprinter's front independent suspension puts the lower ball joints in constant compression under a heavy nose load. On vans in delivery/multi-drop service the lower ball joints wear out very quickly - fleet operators report annual replacement, with highway-mileage vans lastin… Repairs typically run $500-$1,600. Severity: high.
On 3.0L V6 OM642 diesel Sprinters the engine oil cooler sits deep in the valley of the V, sealed to the block by O-rings. The early orange seals harden and shrink from constant heat and weep engine oil, which collects in the valley and runs down the back of the block, often mista… Repairs typically run $900-$2,000. Severity: high.
Sprinter glow plugs fail with age, causing hard starting in cold weather, rough idle when cold, and white smoke on startup. The OM642 V6 is particularly prone to glow plug seizure in the cylinder head, making removal difficult and risking broken glow plugs that require cylinder h… Repairs typically run $300-$1,500. Severity: medium.
On VS30 Sprinters the MBUX multimedia head unit can fail to start after ignition-on and leave the display completely black, or spontaneously reboot roughly 50 seconds after startup. Because the reversing camera image is rendered by MBUX, the same fault means no backup camera pict… Repairs typically run $0-$300. Severity: medium.
On the OM642 the coolant pump and the thermostat housing sit together at the front of the engine and share a common failure story: the pump's shaft seal weeps and the thermostat housing gasket hardens and leaks. Owners report slowly disappearing coolant with no obvious puddle, be… Repairs typically run $500-$1,400. Severity: medium.
The OM642 crankshaft pulley is a harmonic balancer with a bonded rubber ring between an inner hub and outer pulley. With age the rubber degrades and the outer ring separates or wobbles, causing belt-drive vibration, accessory misalignment and squeal. If left unchecked, uncontroll… Repairs typically run $250-$700. Severity: medium.
Sprinters used for city delivery — frequent stops, short trips and long idles — rarely reach the exhaust temperatures needed to complete a DPF regeneration. Soot accumulates until the filter is restricted, lighting the DPF warning, reducing power and eventually forcing limp mode… Repairs typically run $300-$3,000. Severity: medium.
The Sprinter sliding door rollers and track wear out from the heavy door weight and frequent commercial use. The upper and center rollers are most commonly affected, causing the door to become difficult to open or close, bind in the track, or hang crooked. In commercial fleet use… Repairs typically run $200-$800. Severity: low.
Sprinter door lock actuators fail from a mix of water getting past the door seals and rusting the internal mechanism, worn internal gears after years of commercial-duty cycling, and - very commonly on the sliding door and rear barn doors - resistance in the sliding contact block… Repairs typically run $150-$700. Severity: low.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.