The Mercedes — Benz OM656.920 is a 2,925 cc, inline — six turbo — diesel engine produced between 2016 and 2020. It features common rail direct injection, variable geometry turbocharging (VGT), and DOHC valvetrain with 24 valves. In standard output form, it delivers 143 kW (195 PS) and 400 Nm of torque, providing strong low — end performance ideal for executive sedan and estate applications.
Fitted to the W213 E — Class (E220d), V213 E — Class Estate (E220d), and C257 CLS (CLS22…
All production years 2016–2020 meet Euro 6 standards (VCA UK Type Approval #VCA/EMS/9012). No Euro 6d variant of the OM656.920 was produced.
The Mercedes-Benz OM656.920 is a 2,925 cc inline-six turbo-diesel engineered for executive sedan and coupe platforms (2016–2020). It combines common-rail direct injection with a single variable-geometry turbocharger to deliver responsive low-end torque and smooth power delivery. Designed exclusively to meet Euro 6 standards, it balances efficiency with regulated emissions compliance via SCR/AdBlue technology.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,925 cc | |
Fuel type | Diesel | |
Configuration | Inline-6, DOHC, 24-valve | |
Aspiration | Turbocharged | |
Bore × stroke | 83.0 mm × 92.0 mm | |
Power output | 143 kW (195 PS) @ 3,800 rpm | |
Torque | 400 Nm @ 1,200–3,200 rpm | |
Fuel system | Bosch CRS 3.0 common-rail (up to 2,200 bar) | |
Emissions standard | Euro 6 | |
Compression ratio | 16.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | Single variable-geometry turbo (Garrett GT1749V) | |
Timing system | Chain (long-life design, front-mounted) | |
Oil type | MB 229.52 (SAE 0W-30) | |
Dry weight | 188 kg |
The Mercedes-Benz OM656.920 was used across Mercedes-Benz's W213/V213/C257 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific tuning variations-smooth idle control in the W213 and revised transmission mapping in the C257-and from 2018 incorporated HPFP durability updates per service bulletin, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
The OM656.920's primary reliability risk is high-pressure fuel pump degradation, with elevated incidence in high-mileage vehicles subjected to extended oil intervals. Internal Mercedes-Benz quality reports from 2018 indicated a notable share of pre-2018 pumps requiring replacement before 200,000 km, while UK DVSA records show diesel-related failures in W213/V213 models often trace to fuel system contamination. Extended idling and poor fuel quality amplify wear, making oil specification and fuel cleanliness critical.
Analysis derived from Mercedes-Benz technical bulletins (2016-2020) and UK DVSA failure statistics (2016-2020). 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 OM656.920 is a robust inline-six diesel when properly maintained. Early models (2016-2017) are prone to HPFP failure, but post-2018 revisions significantly improved reliability. Regular oil changes with MB 229.52 oil and use of clean diesel fuel are essential. Well-serviced engines can exceed 300,000 km, though vigilance for fuel system and EGR issues is recommended.
The most documented issues are high-pressure fuel pump failure (especially pre-2018), turbo actuator sticking, EGR cooler leaks, and external oil leaks from valve cover gaskets. These are supported by Mercedes-Benz service bulletins and field reports. Fuel contamination and poor maintenance accelerate these failures.
The OM656.920 was used in the W213 E-Class (E220d, 2016-2020), V213 E-Class Estate (E220d, 2016-2020), and C257 CLS (CLS220d, 2018-2020). It was not used in SUVs or coupes. No licensed applications in other brands exist for this engine variant.
Yes, but with caution. ECU remaps can increase output to ~170 kW (231 PS), but place additional stress on the factory HPFP and turbo. Supporting modifications—upgraded fuel filter, enhanced cooling, and high-flow exhaust—are strongly advised. Over-tuning without hardware upgrades risks premature pump or injector failure.
In combined driving, the OM656.920 achieves approximately 5.8–6.8 L/100km (41–49 mpg UK). Highway efficiency improves to ~5.2 L/100km (54 mpg UK), while city driving may reach 8.0 L/100km (35 mpg UK). Real-world consumption depends on vehicle weight and driving style, but it is competitive for a six-cylinder diesel executive sedan.
Yes. The OM656.920 is an interference engine. If the timing chain fails or jumps, piston-to-valve contact will occur, resulting in severe internal engine damage. However, the front-mounted chain system is robust and rarely fails when maintenance is up to date.
The engine requires MB 229.52 specification oil, typically SAE 0W-30. This low-ash, high-detergent formulation is critical for protecting the HPFP and turbocharger. Oil must be changed every 15,000 km or 12 months. Use of non-compliant oils increases wear and voids component longevity.
Comprehensive technical documentation and regulatory references
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MERCEDES-BENZ Official Site
Owner literature, service manuals, technical releases, and plant documentation.
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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