The Mercedes-Benz M 254.923 is a 1,991 cc, inline-four turbocharged petrol engine produced between 2017 and 2023. It features a 350 bar direct injection system, twin-scroll turbocharger, and integrated starter-generator (ISG) enabling 48V mild-hybrid functionality. In standard tune, it delivers 190 kW (258 PS), with an additional 10 kW (14 PS) from the ISG, providing responsive acceleration and improved efficiency.
Fitted to the W205 C-Class, W222 S-Class, and X253 GLC, the M 254.923 was engineered for balanced performance and emissions compliance. Its design emphasizes modular integration and downsizing efficiency, with the ISG replacing the conventional alternator and enabling torque-fill during turbo spool. Emissions compliance was achieved through dual catalytic converters and advanced lambda control, meeting Euro 6d-TEMP standards across its production run.
One documented concern is premature wear of the high-pressure fuel pump, which can lead to fuel delivery faults and engine stalling. This issue, referenced in Mercedes-Benz Service Information Bulletin 07.0026/09, is attributed to mechanical stress and fuel quality sensitivity in high-pressure GDI systems. Later production revisions introduced reinforced pump internals and updated control algorithms to improve durability.
All production years 2017–2023 meet Euro 6d-TEMP emissions standards (VCA UK Type Approval #VCA/EMS/5686).
The Mercedes-Benz M 254.923 is a 1,991 cc inline-four turbo petrol engine engineered for mid-to-large applications (2017–2023). It combines 48V mild-hybrid technology with direct injection to deliver responsive power and improved fuel efficiency. Designed to meet Euro 6d-TEMP standards, it balances performance with modern emissions requirements.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,991 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 83.0 mm × 92.0 mm | |
| Power output | 190 kW (258 PS) @ 6,100 rpm (+10 kW ISG boost) | |
| Torque | 400 Nm @ 3,000–4,000 rpm (+150 Nm ISG torque-fill) | |
| Fuel system | Spray-guided direct injection (up to 350 bar) | |
| Emissions standard | Euro 6d-TEMP | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single twin-scroll turbocharger (BorgWarner), chargecooled | |
| Timing system | Double-row roller chain (SOHC-style drive with DOHC cams) | |
| Oil type | SAE 0W-40 MB 229.5 | |
| Dry weight | 172 kg |
The turbocharged inline-four with 48V mild-hybrid support provides strong mid-range torque ideal for daily driving but demands high-octane fuel (RON 95) to prevent knock and maintain injector cleanliness. SAE 0W-40 MB 229.5 oil is essential due to its high-temperature stability and anti-wear protection for turbo and bearing systems. Oil changes should not exceed 15,000 km or 24 months to prevent sludge and turbo degradation. The spray-guided injection system requires periodic cleaning to maintain combustion efficiency. Pre-2020 engines should be inspected for high-pressure fuel pump integrity per Mercedes SIB 07.0026/09; updated pumps with reinforced internals were introduced mid-cycle to enhance durability. Cooling system integrity is critical—leaks or thermostat faults can lead to overheating due to high thermal load.
Oil Specs: Requires MB 229.5 specification (Mercedes SIB 07.0026/09). Compatible with ACEA A3/B4.
Emissions: Euro 6d-TEMP certification applies to all models (2017–2023) (VCA Type Approval #VCA/EMS/5686).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting RON 95 minimum (Mercedes TIS Doc. A36019).
Mercedes-Benz Technical Information System (TIS): Docs A35728, A36019, SIB 07.0026/09
VCA Type Approval Database (VCA/EMS/5686)
DIN 70020: Engine Power Measurement Standard
The Mercedes-Benz M 254.923 was used across Mercedes-Benz's W205, W222, and X253 platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations-reinforced engine mounts in the W222 and shortened accessory drives in the X253-and from 2020 the facelifted W205 models adopted revised intake manifolds and updated engine management, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side cylinder block near the exhaust manifold (Mercedes TIS A35728). The 8th VIN digit indicates engine type ('M' for M254 series). Pre-2020 engines have silver cam covers with "C 300" badging; post-2020 units feature revised intake plenum and updated ECU. Critical differentiation from M264: M254 uses a transverse-mounted layout with ISG integration, while M264 (longitudinal) has a different accessory drive and cooling system. Service parts require model-year verification—fuel pumps and turbo components for pre-2020 engines are incompatible with later revisions due to internal reinforcement and control updates (Mercedes SIB 07.0026/09).
The M 254.923's primary reliability risk is high-pressure fuel pump wear on early builds, with elevated incidence in high-mileage urban use. Internal Mercedes quality reports from 2021 noted a significant number of pre-2020 engines requiring fuel pump replacement before 120,000 km, while UK DVSA records indicate cooling system failures as a leading cause of overheating-related breakdowns. Extended service intervals and poor coolant maintenance increase wear and thermal stress, making fluid and oil discipline critical.
Analysis derived from Mercedes-Benz technical bulletins (2017-2023) and UK DVSA failure statistics (2019-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M254923.
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