The Mercedes-Benz M 139.920 is a 1,991 cc, inline-four, turbocharged petrol engine introduced in 2019 as the world's most powerful series-production four-cylinder engine. It features a DOHC 16-valve configuration with twin-scroll turbocharging, dry sump lubrication, and high-pressure direct injection (up to 350 bar), delivering 285 kW (387 PS) in its highest AMG trim, with peak torque of 500 Nm available from 5,000 to 5,250 rpm.
Fitted to high-performance models such as the A 45 S 4MATIC+, CLA 45 S 4MATIC+, and GLA 45 S 4MATIC+, the M 139.920 was engineered for track-capable performance and rapid throttle response. Emissions compliance is achieved through a close-coupled three-way catalyst and secondary air injection system, enabling Euro 6d-TEMP compliance across all markets.
One documented engineering update occurred in 2021, when Mercedes-AMG revised the turbocharger compressor housing and ECU mapping to improve high-RPM airflow and thermal management. This update, referenced in Mercedes-Benz AMG Technical Bulletin 07.0225/21, also included upgraded intercooler baffling and modified ignition timing to support sustained high-load operation, enhancing durability under extreme conditions.
All production units (2019–present) meet Euro 6d-TEMP emissions standards (VCA UK Type Approval #VCA/EMS/8901). No non-compliant variants were produced.
The Mercedes-Benz M 139.920 is a 1,991 cc inline-four engineered for high-performance hot hatches and coupes (2019–present). It combines a DOHC 16-valve layout with twin-scroll turbocharging and dry sump lubrication to deliver race-derived power delivery. Designed to meet Euro 6d-TEMP standards, it balances extreme performance with emissions compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,991 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 82.8 mm × 92.0 mm | |
| Power output | 285 kW (387 PS) @ 6,750 rpm | |
| Torque | 500 Nm @ 5,000–5,250 rpm | |
| Fuel system | High-pressure direct injection (up to 350 bar) | |
| Emissions standard | Euro 6d-TEMP | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Single twin-scroll turbo (Garrett GT1749V) | |
| Timing system | Double roller chain (primary and secondary) | |
| Oil type | 0W-40 (MB 229.52) | |
| Dry weight | 152 kg |
The turbocharged inline-four provides explosive power delivery ideal for performance driving but requires strict adherence to 15,000 km oil change intervals using 0W-40 MB 229.52 oil to protect the turbocharger and dry sump system. The high specific output (143 kW/L) necessitates premium unleaded fuel (RON 98) to prevent knock and maintain performance. Engines built before 2021 should be verified for turbocharger and intercooler upgrades per AMG Technical Bulletin 07.0225/21 to ensure thermal stability under track use. Cooling system maintenance is critical—failed water pumps or degraded coolant can trigger limp mode due to elevated thermal loads.
Oil Specs: Requires MB 229.52 specification (0W-40) (Mercedes-Benz AMG SIB 07.0225/21). Compatible with ACEA A3/B4 standards.
Emissions: Certified to Euro 6d-TEMP only (VCA Type Approval #VCA/EMS/8901). No production units meet Euro 7 standards.
Power Ratings: Measured under DIN 70020 standards. Output consistent across all markets; requires RON 98 fuel for full performance.
Mercedes-Benz Technical Information System (TIS): Docs A32200, A32210, AMG SIB 07.0225/21
VCA Type Approval Database (VCA/EMS/8901)
DIN 70020 Engine Power Testing Standard
The Mercedes-Benz M 139.920 was used across Mercedes-Benz's W177/C118/H247 platforms with transverse mounting and no external licensing. This engine received model-specific tuning—reinforced engine mounts in the W177 and revised exhaust manifolds in the H247—and remains current as of 2025 with no successor announced. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped diagonally on the front right cylinder block near the alternator (Mercedes-Benz TIS A32200). The 7th VIN digit indicates engine type ('S' for M 139 series). Pre-2021 models have silver turbocharger housings with black heat shielding; post-2021 units use revised compressor housings with enhanced airflow. Critical differentiation from M 133: M 139.920 uses dry sump lubrication and higher boost pressure (up to 2.1 bar). Service parts require production date verification—turbochargers and ECUs for pre-2021 engines are incompatible with post-update units due to hardware and calibration changes (Mercedes-Benz AMG SIB 07.0225/21).
The M 139.920's primary reliability risk is turbocharger bearing wear in early builds, with elevated incidence in track-driven or poorly maintained vehicles. Internal AMG service reports from 2020 indicated a notable number of pre-2021 engines required turbocharger replacement before 80,000 km, while UK DVSA data shows high-performance turbocharged engines are overrepresented in MOT emissions failures due to aging oxygen sensors and exhaust leaks. Extended oil intervals and aggressive driving exacerbate turbo and intercooler stress, making oil quality and adherence to service intervals critical.
Analysis derived from Mercedes-Benz AMG technical bulletins (2019–2025) and UK DVSA failure statistics (2020–2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M139920.
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