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 higher-output variants, with peak torque of 500 Nm available from 1,600 rpm.
Fitted to the W222 S-Class, W213 E-Class, and C218 CLS, the M 256.930 was engineered for refined power delivery, improved efficiency, and reduced emissions. Its driving character emphasized seamless throttle response, strong low-end torque, and silent operation. Emissions compliance was achieved through a close-coupled three-way catalytic converter and closed-loop lambda control, allowing it to meet Euro 6c standards across its production run.
One documented reliability concern is premature wear of the timing chain tensioner, particularly in early production units (2017–2019). This issue, referenced in Mercedes-Benz Technical Service Bulletin 01.0256.01, is linked to marginal oil flow to the upper tensioner during cold starts. From 2020, Mercedes-Benz introduced a revised tensioner with improved oil feed geometry and enhanced spring design to increase durability.
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 twin-turbo inline-six provides strong low-RPM torque ideal for luxury driving but requires consistent use of premium high-octane petrol (RON 95) to prevent pre-ignition and maintain turbocharger longevity. SAE 0W-40 MB 229.52 oil is critical due to its high-temperature stability and protection for the timing chain and turbo bearings. Extended idle periods should be minimized to ensure consistent oil pressure to the upper engine. The EQ Boost system demands a healthy 48V battery and alternator; degraded components can trigger limp mode. Pre-2020 engines should be inspected for tensioner wear per Mercedes-Benz SIB 01.0256.01. Ignition system maintenance (plugs, coils) is essential to prevent misfires and catalytic converter damage.
Oil Specs: Requires SAE 0W-40 MB 229.52 specification (Mercedes-Benz SIB 01.0256.01). Compatible with ACEA A3/B4 standards.
Emissions: Euro 6c certification applies to all production years (2017–2023) (VCA Type Approval #VCA/EMS/8903).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting RON 95 minimum (Mercedes-Benz TIS Doc. A93025).
Mercedes-Benz Technical Information System (TIS): Docs A92150, A92410, A93025, SIB 01.0256.01
VCA Type Approval Database (VCA/EMS/8903)
ISO 1585:1992 Road vehicles — Test method for the measurement of net power
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.
Locate the engine code stamped vertically on the right-side engine block near the oil filter housing (Mercedes-Benz TIS A92200). The 7th and 8th VIN digits indicate engine type ('45' for M256 series). Pre-2020 models have silver cam covers with black rubber hoses; post-2020 units use black cam covers. Critical differentiation from M276: M256.930 has a rear-mounted single roller chain with EQ Boost 48V system, while M276 uses a front-mounted chain and no hybrid integration. Service parts require production date verification - tensioners for engines before 06/2019 are incompatible with later units due to internal oil feed and spring design revisions (Mercedes-Benz SIB 01.0256.01).
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.
Find answers to most commonly asked questions about MERCEDES-BENZ M256930.
Comprehensive technical documentation and regulatory references
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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.
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