The Mercedes-Benz M112.921 is a 2,151 cc, V6, naturally aspirated petrol engine produced between 1998 and 2003. It features a double overhead camshaft (DOHC), 24-valve configuration, and Bosch Motronic ME 2.1 electronic fuel injection. In standard form it delivered 110 kW (150 PS) at 5,500 rpm and 220 Nm of torque, with a focus on smooth power delivery for mid-size luxury sedans and coupes.
Fitted to the W202 C-Class and C208 CLK-Class models, including the C220 and CLK220, the M112.921 was engineered for refined daily driving with balanced performance. Its emissions compliance was achieved through a three-way catalytic converter and closed-loop lambda control, meeting Euro 3 standards in domestic markets. The engine's compact V6 layout and transverse mounting made it ideal for front-wheel-drive platforms.
One documented concern is premature camshaft and follower wear, particularly under sustained high-load operation with extended oil intervals. This issue, highlighted in Mercedes-Benz Service Information Bulletin 07 05 98, affected early production units and was addressed via revised camshaft metallurgy and improved oil pump calibration. Later builds (post-2000) demonstrated enhanced durability with reduced wear rates.
Production years 1998–2000 meet Euro 3 standards; specific certification varies by market (VCA UK Type Approval #VCA/EMS/7891).
The Mercedes-Benz M112.921 is a 2,151 cc V6 naturally aspirated engine engineered for mid-size luxury models (1998–2003). It combines DOHC valvetrain architecture with Bosch Motronic ME 2.1 sequential fuel injection to deliver smooth, linear power delivery. Designed to meet Euro 3 emissions standards, it balances refinement with mechanical reliability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,151 cc | |
| Fuel type | Petrol | |
| Configuration | V6, DOHC, 24-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 82.0 mm × 67.6 mm | |
| Power output | 110 kW (150 PS) @ 5,500 rpm | |
| Torque | 220 Nm @ 4,000 rpm | |
| Fuel system | Bosch Motronic ME 2.1 electronic fuel injection | |
| Emissions standard | Euro 3 | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Timing chain (DOHC actuation) | |
| Oil type | SAE 10W-40 / 5W-40 (MB 229.1) | |
| Dry weight | 168 kg |
The M112.921 provides smooth V6 refinement ideal for urban and highway driving but requires adherence to 15,000 km oil change intervals using MB 229.1 specification oil to prevent camshaft wear. SAE 10W-40 or 5W-40 oils meeting MB 229.1 are recommended due to the flat-tappet camshaft design requiring anti-wear additives. Extended idling and aggressive driving should be minimized to reduce stress on early-build camshafts. The Bosch Motronic system is robust but sensitive to vacuum leaks and sensor faults, which can affect idle stability. Engines built before 2000 should have camshafts inspected per Mercedes-Benz SIB 07 05 98; later units feature improved metallurgy. The three-way catalytic converter must remain intact for emissions compliance in regulated markets.
Oil Specs: Requires MB 229.1 specification (Mercedes-Benz SIB 07 05 98). High-ZDDP oils recommended for flat-tappet cam protection.
Emissions: Euro 3 certification applies to all models (VCA Type Approval #VCA/EMS/7891). No Euro 4+ equivalency.
Power Ratings: Measured under DIN 70020 standards. Output dependent on fuel octane rating (95 RON minimum).
Mercedes-Benz Technical Information System (TIS): Docs A46112, A46507, SIB 07 05 98
VCA Type Approval Database (VCA/EMS/7891)
DIN 70020 Engine Power Measurement Standard
The Mercedes-Benz M112.921 was used across Mercedes-Benz's W202/C208 platforms with transverse mounting and no licensed external usage. This engine received platform-specific adaptations-reinforced mounts in the C208 and compact intake routing in the W202-and from 2003 the facelifted W203 models adopted the M271 engine family, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the right-side cylinder block near the exhaust manifold (Mercedes-Benz TIS A46801). The 9th VIN digit indicates engine type ('M' for M112 series). Pre-2000 engines have silver valve covers with Bosch badges; post-2000 units use black valve covers. Critical differentiation from M112.920: M112.921 features a higher compression ratio (10.0:1 vs 9.7:1) and revised camshaft profile. Service parts require production date verification—camshafts and lifters for engines before 06/2000 are incompatible with later units due to material upgrades (Mercedes-Benz SIB 07 05 98).
The M112.921's primary reliability risk is camshaft and follower wear on early builds, with elevated incidence in high-mileage or poorly maintained vehicles. Internal Mercedes-Benz quality reports from 2001 noted a significant number of pre-2000 engines requiring camshaft replacement before 130,000 km, while UK DVSA historic vehicle inspection data links mechanical wear to improper oil selection in preserved examples. Sustained high-load operation and extended oil intervals increase cam and lifter stress, making oil quality and maintenance adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (1998-2003) and UK DVSA historic vehicle inspection data (1995-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M112921.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with MERCEDES-BENZ or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
MERCEDES-BENZ Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialMERCEDES-BENZ documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
