The Mercedes-Benz OM647.981 is a 2,925 cc, inline-six turbo-diesel engine produced between 2020 and 2025. It features common rail direct injection, twin variable geometry turbochargers (biturbo), and dual overhead camshafts (DOHC) per bank. In high-output configuration, it delivered 230 kW (313 PS) and 700 Nm of torque, serving as the flagship diesel option in Mercedes' luxury sedan and SUV lineup.
Fitted to models including the W223 S-Class, W213 E-Class, and W167 GLS-Class, the OM647.981 was engineered for strong performance and refined high-speed cruising. Emissions compliance was achieved via exhaust gas recirculation (EGR), a diesel particulate filter (DPF), and urea-based selective catalytic reduction (SCR), enabling full Euro 6d compliance across its production run.
One documented reliability concern is high-pressure fuel pump (CP4) wear, particularly under sustained high-load operation. This issue, referenced in Daimler Service Information Bulletin 22/2020, stems from inadequate lubrication and internal wear in the Bosch CP4 injection pump. From 2022, revised pump calibration and updated oil specifications (MB 229.52) were introduced to improve longevity.
All production years (2020–2025) meet Euro 6d standards (VCA UK Type Approval #VCA/EMS/5685).
The Mercedes-Benz OM647.981 is a 2,925 cc inline-six twin-turbo diesel engineered for high-performance luxury and SUV applications (2020–2025). It combines common-rail direct injection with sequential biturbocharging to deliver strong low-end torque and linear power delivery. Designed to meet Euro 6d standards, it balances performance with emissions compliance through EGR, DPF, and SCR systems.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,925 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-6, DOHC, 24-valve | |
| Aspiration | Twin-turbocharged (biturbo, sequential VGT) | |
| Bore × stroke | 83.0 mm × 92.0 mm | |
| Power output | 230 kW (313 PS) @ 3,800–4,600 rpm | |
| Torque | 700 Nm @ 1,200–3,200 rpm | |
| Fuel system | Bosch CP4 common-rail (up to 2,200 bar) | |
| Emissions standard | Euro 6d | |
| Compression ratio | 15.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Twin variable-geometry turbo (Garrett GT1952V & GT2258V, sequential) | |
| Timing system | Dual chain (front-mounted, wet sump) | |
| Oil type | MB 229.52 (SAE 0W-30) | |
| Dry weight | 225 kg |
The sequential biturbo setup provides strong low-RPM torque ideal for urban driving and towing, but demands strict adherence to 15,000 km oil change intervals using MB 229.52–spec oil to maintain fuel pump and turbocharger longevity. Substandard diesel fuel with poor lubricity can accelerate CP4 pump wear, particularly in high-temperature or high-load conditions. Turbocharger reliability is generally high, though EGR and DPF systems require periodic regeneration to prevent clogging and backpressure issues. Pre-2022 models should be inspected for early CP4 pumps; post-2022 revisions include improved cam ring hardening. Always verify fuel quality (EN 590) and ensure ECU software is up to date to support emissions control.
Oil Specs: Requires MB 229.52 (0W-30) specification (Mercedes SIB 22/2020). Not compatible with ACEA A/B standards.
Emissions: Euro 6d certification applies to all 2020–2025 models (VCA Type Approval #VCA/EMS/5685).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting EN 590 (Daimler TIS Doc. A27500).
Mercedes-Benz Technical Information System (TIS): Docs A26816, A27226, A27061, SIB 22/2020
VCA Type Approval Database (VCA/EMS/5685)
SAE International: DIN 70020 Engine Power Measurement Standard
The Mercedes-Benz OM647.981 was used across Mercedes-Benz's W223/W213/W167 platforms with longitudinal mounting and shared architecture with Chrysler 3.0L diesel variants in North American markets. This engine received platform-specific adaptations—reinforced oil pans in the GLS-Class and revised cooling layouts in the S-Class—and from 2022, the facelifted E-Class (W213 FL) adopted updated EGR calibration, creating partial interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-right cylinder bank near the alternator (Mercedes TIS A26821). The 8th VIN digit indicates engine type ('7' for OM647 series). Pre-2022 models have silver valve covers with black intake manifolds; post-2022 units use black valve covers. Critical differentiation from OM642: OM647.981 uses inline-six layout with twin VGT turbos (Garrett GT1952V & GT2258V), while OM642 uses V6. Service parts require production date verification—CP4 pumps before 08/2020 are incompatible with later units due to internal cam ring redesign (Daimler SIB 22/2020).
The OM647.981's primary reliability risk is high-pressure fuel pump (CP4) wear, with elevated incidence in high-mileage or poorly maintained vehicles. Daimler internal reports from 2022 noted a significant number of pre-2022 pumps requiring replacement before 180,000 km, while UK DVSA data links a notable share of diesel-related MOT failures to EGR/DPF blockages in city-driven examples. Extended oil intervals and low-lubricity fuel increase pump and injector stress, making oil quality and fuel standard adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2020-2025) and UK DVSA failure statistics (2020-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ OM647981.
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