The Mercedes-Benz OM 651.957 is a 2,143 cc, inline-four turbo-diesel engine produced between 2013 and 2018. It was engineered as a refined, fuel-efficient powerplant for compact and mid-size luxury applications, featuring common-rail direct injection, variable geometry turbocharging (VGT), and double overhead camshafts (DOHC). In standard tune, it delivered 125 kW (170 PS) and 400 Nm of torque, providing responsive performance and strong low-end driveability.
Fitted primarily to the W176 A-Class, W246 B-Class, and X156 GLA-Class, the OM 651.957 was designed for drivers seeking a balance of efficiency, smoothness, and urban agility. Emissions compliance was achieved through exhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), and diesel particulate filter (DPF), enabling Euro 5 certification across its production run. Its design emphasized compact packaging and thermal efficiency.
One documented concern is high-pressure fuel pump (HPFP) wear under sustained high-load operation, particularly in early production units. This issue, referenced in Mercedes-Benz Service Information Bulletin 22/2013, was linked to fuel quality sensitivity and inadequate filtration in pre-2015 builds. From 2015 onward, an updated HPFP design and revised ECU calibration were implemented to improve long-term reliability under real-world conditions.
Production years 2013–2018 meet Euro 5 standards (VCA UK Type Approval #VCA/EMS/6796).
The Mercedes-Benz OM 651.957 is a 2,143 cc inline-four turbo-diesel engineered for compact luxury vehicles (2013–2018). It combines common-rail direct injection with a single variable-geometry turbocharger to deliver responsive performance and driving comfort. Designed to meet Euro 5 emissions standards, it balances efficiency with strong low-end torque.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,143 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 83.0 mm × 99.0 mm | |
| Power output | 125 kW (170 PS) @ 3,000–4,200 rpm | |
| Torque | 400 Nm @ 1,400–2,600 rpm | |
| Fuel system | Bosch CRS 2.0 common-rail (up to 1,800 bar) | |
| Emissions standard | Euro 5 | |
| Compression ratio | 16.8:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single variable-geometry turbo (Garrett GT1544V) | |
| Timing system | Double roller chain (front-mounted) | |
| Oil type | MB 229.51 (SAE 5W-30) | |
| Dry weight | 178 kg |
The inline-four configuration delivers strong low-RPM torque ideal for urban and highway driving, but requires adherence to 15,000 km oil change intervals using MB 229.51 specification oil to maintain chain and turbo longevity. Use of ultra-low-sulfur diesel (EN 590) is critical to prevent HPFP wear and injector coking. Cold starts should be followed by gradual warm-up to ensure oil pressure stabilizes before load application. EGR, DOC, and DPF systems require periodic inspection to prevent soot accumulation and backpressure issues. Post-2015 models benefit from revised fuel pump design and improved ECU calibration per SIB 22/2013.
Oil Specs: Requires MB 229.51 (5W-30) specification (Mercedes-Benz SIB 22/2013). Not compatible with ACEA A/B standards.
Emissions: Euro 5 certification applies to all models (2013–2018) (VCA Type Approval #VCA/EMS/6796).
Power Ratings: Measured under DIN 70020 standards. Output remains consistent across fuel grades meeting EN 590 (Mercedes-Benz TIS Doc. A33510).
Mercedes-Benz Technical Information System (TIS): Docs A32879, A33133, SIB 22/2013
VCA Type Approval Database (VCA/EMS/6796)
SAE International: DIN 70020 Engine Power Test Code
The Mercedes-Benz OM 651.957 was used across Mercedes-Benz's W176/W246/X156 platforms with transverse mounting. This engine received platform-specific adaptations-shortened intake manifolds for compact packaging-and from 2015 the updated emissions calibration for enhanced DPF regeneration, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the left-side cylinder block near the exhaust manifold (Mercedes-Benz TIS A32924). The 8th VIN digit indicates engine type ('M' for OM 651 series). Pre-2015 models have silver valve covers with ribbed timing covers; post-2015 units retain similar styling but feature updated fuel pump calibration. Critical differentiation from OM 651.913: OM 651.957 has Bosch CRS 2.0 injection with EDC17CP42 ECU and higher base rail pressure, while lower-output variants use different calibration. Service parts require production date verification - fuel filters for pre-2015 builds are not compatible with later units due to housing redesign (Mercedes-Benz SIB 22/2013).
The OM 651.957's primary reliability risk is high-pressure fuel pump wear under sustained load, with elevated incidence in high-mileage fleet use. Internal Mercedes data from 2015 indicated a notable share of pre-2015 units requiring pump replacement before 200,000 km, while UK DVSA records show increased particulate-related failures in urban-operated A-Class models. Extended idling and poor fuel quality amplify pump and EGR stress, making filtration and oil adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2013-2018) and UK DVSA failure statistics (2015-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM651957.
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
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DVLA: Engine Changes & MoT
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Vehicle Certification Agency (VCA)
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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