The Mercedes-Benz OM651.911 is a 2,143 cc, inline-four turbo-diesel engine produced between 2011 and 2016. It was engineered as a compact, high-efficiency powerplant for executive and premium compact vehicles, featuring common-rail direct injection, variable geometry turbocharging (VGT), and dual overhead camshafts (DOHC). In standard output, it delivered 100 kW (136 PS) and 300 Nm of torque, with higher-output variants reaching 125 kW (170 PS), offering responsive performance and strong low-end pulling power for urban and highway driving.
Fitted to the W204 C-Class, W246 B-Class, and W176 A-Class, the OM651.911 was designed for fuel efficiency, driving refinement, and emissions compliance in premium compact and mid-size platforms. Emissions compliance was achieved through cooled exhaust gas recirculation (EGR), a diesel particulate filter (DPF), and selective catalytic reduction (SCR) with AdBlue dosing, enabling Euro V certification across its production run. Its design emphasizes NVH reduction and thermal durability under sustained load.
One documented reliability concern is premature high-pressure fuel pump wear, particularly in early-series units (2011–2013). Highlighted in Daimler Service Information Bulletin 20-05-006, the issue is linked to marginal fuel filtration and sensitivity to low-lubricity diesel. From 2014, revised pump calibration and updated fuel filter specifications (A 001 475 52 03) were implemented to improve longevity.
Production years 2011–2016 meet Euro V standards (VCA UK Type Approval #VCA/DIESEL/OM651).
The Mercedes-Benz OM651.911 is a 2,143 cc inline-four turbo-diesel engineered for premium compact and mid-size platforms (2011–2016). It combines Bosch common-rail injection (up to 1,800 bar) with a variable-geometry turbocharger to deliver strong low-RPM torque. Designed to meet Euro V emissions standards, it balances efficiency with regulated environmental performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,143 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged with VGT | |
| Bore × stroke | 83.0 mm × 99.0 mm | |
| Power output | 100–125 kW (136–170 PS) | |
| Torque | 300–400 Nm @ 1,400–2,800 rpm | |
| Fuel system | Bosch CRS 2.0 common-rail (1,800 bar max) | |
| Emissions standard | Euro V | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Garrett GT1544V VGT | |
| Timing system | Chain-driven (dual-row, service-interval critical) | |
| Oil type | MB 229.5 or MB 229.51 | |
| Dry weight | 178 kg |
The OM651.911 delivers responsive low-RPM torque ideal for urban and mixed driving but requires strict adherence to fuel quality standards to prevent high-pressure pump and injector wear. MB 229.5 or MB 229.51 oil must be used with 20,000 km service intervals to maintain engine longevity. Ultra-low sulfur diesel (ULSD, EN 590) and regular AdBlue replenishment are mandatory to prevent EGR, DPF, and SCR system fouling. The dual-row timing chain system demands timely replacement per manufacturer schedule—failure to service can result in catastrophic engine damage. Early units (pre-2014) should have pump recalibration per Daimler SIB 20 05 006 to mitigate premature failure. Active regeneration cycles must be completed monthly to maintain DPF efficiency in city-driven vehicles.
Oil Specs: Requires MB 229.5 or MB 229.51 specification (Daimler SIB 20 05 006). Compatible with ACEA B5/B6 standards.
Emissions: Euro V certification applies to all models (2011–2016) (VCA Type Approval #VCA/DIESEL/OM651).
Power Ratings: Measured under ISO 1585. Higher outputs (170 PS) require full AdBlue system functionality (Daimler TIS M133000).
Daimler Technical Information System (TIS): Docs M133000, M133001, SIB 20 05 006
VCA Type Approval Database (VCA/DIESEL/OM651)
ISO 1585: Road vehicles — Engine test code — Net power
The Mercedes-Benz OM651.911 was used across Mercedes-Benz's W204, W246, and W176 platforms with transverse mounting and no licensed external applications. This engine received platform-specific adaptations-shorter accessory drives in the W176 and reinforced EGR routing in the W246-and from 2016 was succeeded by the OM654 for modular diesel architecture, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine ID plate mounted on the left-side cylinder block near the oil filter housing (Daimler TIS M133004). The 7th digit of the VIN indicates engine type ('K' for OM651 series). Pre-2014 units have a Bosch CP3.3 high-pressure pump; post-2014 revisions use CP3.4 with dual filtration. Critical differentiation from OM646: OM651.911 is a 2.1L inline-four with 83 mm bore and uses a Garrett VGT turbo, while OM646 is a 3.0L inline-six. Service parts require chassis number verification—fuel pumps for pre-2014 models are incompatible with later units due to calibration differences (Daimler SIB 20 05 006).
The OM651.911's primary reliability risk is high-pressure fuel pump wear in early builds, with elevated incidence in regions with inconsistent fuel quality. Daimler internal reports from 2013 indicated over 11% of pre-2013 units required pump replacement before 200,000 km, while VCA field data shows Euro V DPF systems in city-driven fleets require cleaning every 60,000–80,000 km. Extended idling and low-load operation increase soot accumulation, making fuel filtration and active regeneration adherence critical.
Analysis derived from Daimler technical bulletins (2011-2016) and UK DVSA failure statistics (2016-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM651911.
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Regulation (EC) No 715/2007
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