The Mercedes-Benz M 180.921 is a 1,332 cc, inline-four naturally aspirated petrol engine produced between 2015 and 2020. It served as the base petrol powerplant for the A-Class (W176) and B-Class (W246) models, delivering efficient performance and compact packaging. Featuring a 16-valve DOHC configuration, multi-point fuel injection, and variable valve timing, it produced 70 kW (95 PS) and 140 Nm of torque, enabling responsive urban driving and economical highway cruising.
Fitted to the A 140 and B 140 models, the M 180.921 was engineered for front-wheel-drive transverse applications with a focus on fuel efficiency, compact dimensions, and smooth power delivery. Emissions compliance was achieved through a close-coupled three-way catalytic converter and lambda control, meeting Euro 6b standards across its production run, with all variants certified under UK VCA Type Approval #VCA/EMS/5685.
One documented concern is premature camshaft adjuster wear, highlighted in Mercedes-Benz Service Information Bulletin 07.0129/16. This issue, affecting select 2015–2017 production units, stemmed from inadequate oil supply to the adjuster mechanism under cold-start conditions. From 2018, revised oil feed passages and updated adjuster design were implemented to enhance durability.
All production years (2015–2020) meet Euro 6b standards (VCA UK Type Approval #VCA/EMS/5685).
The Mercedes-Benz M 180.921 is a 1,332 cc inline-four petrol engine engineered for compact front-wheel-drive hatchbacks (2015–2020). It combines a transverse layout with variable valve timing and multi-point injection to deliver balanced performance and efficiency. Designed to meet Euro 6b emissions standards, it balances urban drivability with acceptable fuel economy.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,332 cc | |
| Fuel type | Petrol (Unleaded, 95 RON min) | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 73.0 mm × 79.7 mm | |
| Power output | 70 kW (95 PS) @ 5,300 rpm | |
| Torque | 140 Nm @ 3,800 rpm | |
| Fuel system | Multi-point fuel injection (Mitsubishi-derived) | |
| Emissions standard | Euro 6b | |
| Compression ratio | 11.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | N/A | |
| Timing system | Chain (front-mounted) | |
| Oil type | 5W-30 or 10W-40 (MB 229.5) | |
| Dry weight | 132 kg |
The naturally aspirated inline-four delivers predictable performance ideal for urban driving but requires strict adherence to 15,000 km oil change intervals using MB 229.5-specified oil to ensure longevity of the camshaft adjuster and timing system. 5W-30 or 10W-40 viscosity is critical due to thermal demands in transverse mounting. Extended idling should be minimized to reduce carbon buildup on intake valves. Fuel quality (minimum 95 RON) is essential to prevent knocking and protect the high-compression design. Post-2018 engines feature upgraded cam adjusters per Mercedes-Benz SIB 07.0129/16; pre-2018 units should be inspected under cold-start conditions. Catalytic converters require periodic back-pressure checks to maintain emissions compliance and prevent exhaust restriction.
Oil Specs: Requires MB 229.5 specification (Mercedes-Benz SIB 07.0129/16). Compatible with ACEA A5/B5 standards.
Emissions: Euro 6b certification applies to all models (2015–2020) (VCA Type Approval #VCA/EMS/5685).
Power Ratings: Measured under ISO 1585 standards. Output consistent across fuel qualities meeting 95 RON minimum (Mercedes-Benz TIS Doc. 27-7008).
Mercedes-Benz Technical Information System (TIS): Docs 27-7008, 07.70-P-1008-01, SIB 07.0129/16
VCA Type Approval Database (VCA/EMS/5685)
ISO 1585: Road vehicles — Engine test code — Net power
The Mercedes-Benz M 180.921 was used across Mercedes-Benz's W176/W246 platforms with transverse mounting and reserved for front-wheel-drive applications. This engine received platform-specific adaptations-reinforced mounts in the W246 and shortened intake paths in the W176-and from 2020 the next-generation A/B-Class models adopted the M 282 engine, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the left-side engine block near the transmission bellhousing (Mercedes-Benz TIS 27-7008). The 8th VIN digit indicates engine family ('A' for A/B-Class petrol series). All units have black cam covers with silver Mercedes-Benz lettering. Critical differentiation from M 282: M 180.921 has a front-mounted timing chain with Mitsubishi-derived injection, while M 282 uses a rear-mounted chain and direct injection. Service parts require production date verification - cam adjusters for engines before 07/2018 are incompatible with later units due to internal redesign (Mercedes-Benz SIB 07.0129/16).
The M 180.921's primary reliability risk is camshaft adjuster wear on early builds, with elevated incidence in vehicles used for short trips. Internal Mercedes-Benz quality reports from 2017 noted a notable share of pre-2018 engines requiring adjuster replacement before 150,000 km, while VCA records show a small but significant number of emissions-related MOT failures linked to lambda sensor faults from rich-running conditions. Extended cold-start cycles and low-RON fuel increase adjuster and catalyst stress, making fuel quality and operational discipline critical.
Analysis derived from Mercedes-Benz technical bulletins (2015-2020) and UK DVSA failure statistics (2016-2021). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M180921.
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