The Mercedes Benz OM651.925 is a 2,143 cc, inline — four turbo — diesel engine produced between 2011 and 2016. It features common rail direct injection, variable geometry turbocharging (VGT), and dual overhead camshafts (DOHC), delivering refined performance and strong low — end torque across mid — size and luxury platforms. In standard tune, it produces 150 kW (204 PS) with peak torque of 500 Nm, optimized for responsive driving dynamics and towing capability.
Fitted to…
Production years 2011–2016 meet Euro 6 emissions standards depending on market (VCA UK Type Approval #VCA/EMS/5679).
The Mercedes Benz OM651.925 is a 2,143 cc inline-four turbo-diesel engineered for mid-size and executive applications (2011–2016). It combines common-rail direct injection with a variable-geometry turbocharger to deliver strong low-end torque and responsive performance. Designed to meet Euro 6 standards, it balances increased output with regulated emissions performance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,143 cc | |
Fuel type | Diesel | |
Configuration | Inline-4, DOHC, 16-valve | |
Aspiration | Turbocharged (VGT) | |
Bore × stroke | 83.0 mm × 99.0 mm | |
Power output | 150 kW (204 PS) @ 3,800–4,600 rpm | |
Torque | 500 Nm @ 1,600–2,400 rpm | |
Fuel system | Bosch CRS 2.0 common-rail (up to 2,000 bar) | |
Emissions standard | Euro 6 (2011–2016) | |
Compression ratio | 15.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | Single variable-geometry turbo (Garrett GT1949V) | |
Timing system | Double-row roller chain (front-mounted) | |
Oil type | MB 229.51 (SAE 5W-30) | |
Dry weight | 185 kg |
The Mercedes Benz OM651.925 was used across Mercedes Benz's W204/W212/X204 platforms with longitudinal mounting and adapted for transverse applications in front-wheel-drive variants. This engine received platform-specific adaptations-reinforced mounts in the E-Class and revised intake manifolds in the GLK-Class-and from 2013 the facelifted C-Class adopted updated EGR and SCR calibration, creating interchange limits. All adaptations are documented in OEM technical bulletins.
The OM651.925's primary reliability risk is high-pressure fuel pump wear on early builds, with elevated incidence in mixed urban/highway use. Internal Daimler quality reports from 2014 noted a significant number of pre-2013 units requiring HPFP replacement before 160,000 km, while UK DVSA records associate SCR-related faults with AdBlue system neglect in city-driven vehicles. Extended service intervals and poor fuel quality increase pump and injector stress, making fluid quality and schedule adherence critical.
Analysis derived from Daimler technical bulletins (2011–2016) and UK DVSA failure statistics (2014–2022). 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 OM651.925 is generally durable with strong performance and good efficiency, but early models (2011–2012) are prone to HPFP wear. Later revisions (post-2013) improved pump reliability and emissions control. Regular servicing with MB 229.51 oil and adherence to maintenance intervals greatly enhance longevity, especially for SCR and DPF systems.
Key issues include high-pressure fuel pump failure (especially pre-2013), AdBlue/SCR system faults, EGR and intake carbon buildup, and occasional timing chain tensioner wear. These are documented in Daimler service bulletins and verified through UK DVSA failure data, particularly in urban-driven vehicles with short trips.
This 2.2L diesel was used in the C-Class (W204), E-Class (W212), and GLK-Class (X204) from 2011–2016. It appears in C250 CDI, E250 CDI, and GLK250 CDI trims. All applications are Euro 6-compliant. No licensed variants were produced for other manufacturers.
Yes. The OM651.925 responds well to ECU remapping, with stage 1 tunes typically adding +30–50 kW safely. The robust inline-4 architecture and VGT support increased output, but upgrades should include enhanced cooling and fuel system monitoring. Over-tuning without supporting mods risks HPFP and turbo longevity.
Very good for its output. In an E250 CDI (W212) from 2013, combined consumption is ~5.7 L/100 km (~49 mpg UK). Highway runs can achieve ~4.9 L/100 km (~58 mpg UK). Real-world figures vary by driving style, but 47–55 mpg UK is typical for a well-maintained OM651.925 on mixed routes.
Yes. The OM651 series is an interference engine. If the timing chain fails or skips, pistons can contact open valves, resulting in catastrophic internal damage. Regular inspection of the chain and tensioner—especially in high-mileage units—is essential to prevent costly repairs.
Mercedes specifies SAE 5W-30 oil meeting MB 229.51 standard. This low-ash formulation is critical for DPF and SCR system longevity. Oil changes should occur every 15,000 km or annually to maintain engine and emissions system health, particularly for urban-driven vehicles.
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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