The Mercedes — Benz M 256.930 is a 2,999 cc, inline — six twin — turbocharged petrol engine produced between 2017 and 2023. It serves as the new — generation inline — six powerplant for Mercedes — Benz's luxury and performance lineup, replacing the aging V6 and V8 naturally aspirated engines. Featuring a 30° canted DOHC 24 — valve configuration, integrated exhaust manifold, and EQ Boost 48V mild — hybrid system, it produced 270 kW (367 PS) in base form and up to 320 kW (435 PS) in hi…
Production years 2017–2023 meet Euro 6c emissions standards (VCA UK Type Approval #VCA/EMS/8903).
The Mercedes-Benz M 256.930 is a 2,999 cc inline-six twin-turbocharged engine engineered for luxury and performance platforms (2017–2023). It combines a DOHC 24-valve architecture with EQ Boost mild-hybrid technology to deliver responsive low-end torque and fuel efficiency. Designed to meet Euro 6c standards, it balances modern drivability with emissions compliance for its era.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,999 cc | |
Fuel type | Petrol | |
Configuration | Inline-6, DOHC, 24-valve | |
Aspiration | Twin-turbocharged | |
Bore × stroke | 83.0 mm × 92.0 mm | |
Power output | 270–320 kW (367–435 PS) @ 5,500–6,100 rpm | |
Torque | 500 Nm @ 1,600–4,500 rpm | |
Fuel system | HFM-SFI direct port fuel injection | |
Emissions standard | Euro 6c | |
Compression ratio | 10.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | Twin-scroll turbochargers with electric auxiliary compressor (BorgWarner) | |
Timing system | Single roller chain (rear-mounted) | |
Oil type | SAE 0W-40 MB 229.52 | |
Dry weight | 186 kg |
The Mercedes-Benz M 256.930 was used across Mercedes-Benz's W222/W213/C218 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-reinforced mounts in the W222 and modified intake manifolds in the C218-and from 2020 the facelifted W213 models adopted revised turbocharger calibration for improved low-end response, creating minor service part differences. All adaptations are documented in OEM technical bulletins.
The M 256.930's primary reliability risk is premature timing chain tensioner wear on early builds, with elevated incidence in high-mileage, urban-driven vehicles. Internal Mercedes-Benz quality reports from 2020 indicated a significant number of pre-2020 engines required tensioner replacement before 100,000 km, while UK DVSA records show a notable rate of MoT failures due to exhaust emissions exceeding limits linked to valve timing drift. Sustained stop-start cycling and delayed oil changes increase chain and tensioner stress, making oil quality and interval adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2017-2023) and UK DVSA failure statistics (2018-2024). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The M 256.930 is a modern turbocharged inline-six with strong mechanical design, but early models (2017–2019) are prone to timing chain tensioner wear. Later revisions (post-2020) significantly improved durability. With meticulous maintenance, including regular oil changes with MB 229.52 spec oil and use of high-octane fuel, well-maintained examples can exceed 150,000 km. Neglect, especially with oil and coolant, leads to expensive repairs.
The primary issues are premature timing chain tensioner wear (pre-2020), vacuum leaks from deteriorating intake hoses, ignition system failures (coils, plugs), and coolant leaks from heater lines and the thermostat housing. These are documented in Mercedes-Benz service bulletins and are typical of high-mileage inline-six engines from this era. Regular inspection of hoses and electrical components is essential.
The M 256.930 powered the mid-to-high-end variants of the S-Class, E-Class, and CLS lineups. It was used in the W222 S-Class (S 450, S 500), W213 E-Class (E 450, E 500), and C218 CLS (CLS 450, CLS 53 AMG). All applications met Euro 6c emissions standards. No external manufacturers licensed this engine.
Yes, moderately. ECU remapping is widely available and can yield +30-50 kW gains safely on stock internals. Performance upgrades like exhaust, intercooler, and throttle bodies are common. However, the EQ Boost system and turbocharger limits must be respected. The engine's strength lies in its broad torque curve and efficiency when stock, though tuning requires careful cooling and fuel management.
Fuel consumption is moderate by modern standards. In an E 500 (W213), expect ~10.5 L/100km (city) and ~7.5 L/100km (highway), approximately 36 mpg UK combined. Real-world figures depend heavily on driving style. The turbocharged inline-six and mild-hybrid system result in efficient fuel use, especially on longer journeys.
Yes. The M 256.930 is an interference engine. If the timing chain fails or jumps, the pistons can collide with the open valves, causing catastrophic internal damage. While the rear-mounted single roller chain is robust, any signs of chain rattle or tensioner failure must be addressed immediately to prevent engine destruction.
Mercedes-Benz specifies SAE 0W-40 oil meeting MB 229.52 specification. This oil is critical for protecting the timing chain and turbocharger, especially in pre-2020 engines. Change intervals should not exceed 15,000 km or one year, whichever comes first, to ensure optimal lubrication and prevent premature wear.
Comprehensive technical documentation and regulatory references
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MERCEDES-BENZ Official Site
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EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
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