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Mercedes-Benz M112 Engine - Replacement Cost, Problems & CompatibilityProblems & Compatibility
The M112 is Mercedes-Benz’s legendary 2.4-litre to 3.2-litre V6 petrol engine, famous for its smooth power delivery, 3-valve-per-cylinder design, and the introduction of the high-performance "Kompressor" (supercharged) AMG variants. Fitted to the W202/W203 C-Class, W210/W211 E-Class, W208 CLK, and R170 SLK, reconditioned M112 engines typically start from £1,800 , serving as a highly sought-after, robust unit for classic Mercedes restorations and daily-driven vintage hosts.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
Used from
£600
Reconditioned from
£1,800
Rebuilt from
£2,800
GB
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Key Specs
Mercedes-Benz M112 - Specifications at a Glance
Engine Code
M112 (including M112.910, M112.920, M112.940, M112.950, M112.960)
Fuel
Petrol
Configuration
2.4L-3.2L V6, SOHC, 18-valve (3 valves per cylinder), Port Fuel Injection
Power Output(s)
125 kW (170 hp) - 260 kW (354 hp, Supercharged AMG)
Years Produced
1996-2005
UK Models Fitted
5 Mercedes model families - full list in Compatibility below
Replaced
M104 / M103
Replaced By
M272
Most Common Failure
Crankshaft position sensor (CPS) failure and balance shaft gear wear
Reconditioned Price Range
£1,800-£3,000 supply-only
Vetted UK specialists for M112 replacements
Minimum 12-month warranty on reconditioned and rebuilt options
Fitted To
Which Mercedes Models Use the M112-
The M112 was the definitive V6 petrol for Mercedes-Benz throughout the late 1990s and early 2000s, bridging the gap between the older inline-6 M104 and the modern M272, offering exceptional smoothness, reliability, and the legendary C32/SLK32 AMG supercharged variants.
| Model | Generation/Chassis | Badge(s) | Years | Link |
|---|---|---|---|---|
 Mercedes-Benz C-Class | W202 / W203 | C 240, C 280, C 320, C 32 AMG | 1997-2005 | |
| Mercedes-Benz E-Class | W210 / W211 | E 240, E 280, E 320 | 1996-2005 | |
| Mercedes-Benz CLK-Class | W208 / W209 | CLK 240, CLK 320 | 1997-2005 | |
| Mercedes-Benz SLK-Class | R170 | SLK 320, SLK 32 AMG | 1999-2004 | |
| Mercedes-Benz S-Class | W220 | S 320 | 1998-2002 |
02
Mercedes-Benz E-Class
03
Mercedes-Benz CLK-Class
04
Mercedes-Benz SLK-Class
05
Mercedes-Benz S-Class
CROSS-BRAND
M112 is documented across 5 BMW applications spanning C-Class, E-Class, CLK-Class, SLK-Class, S-Class. Registration lookup confirms the exact suffix before quotes are sent.
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Prices
Mercedes-Benz M112 Engine Replacement Cost (UK)
Condition | Supply Only | Fitted (Independent Specialist) | Typical Warranty |
|---|---|---|---|
Used | £600-£1,200 | £1,200-£2,100 | 3-6 months |
Reconditioned | £1,800-£3,000 | £2,500-£4,000 | 12-24 months |
Rebuilt | £2,800-£4,500 | £3,600-£5,500 | 12-24 months |
What genuinely moves the price for this engine is the condition of the balance shaft assembly, timing chain tensioners, and the crankshaft position sensor (CPS) wiring. Because the M112 is a robust but aging V6, recon specialists will typically replace the balance shaft gears, fit a new timing chain kit, and replace all brittle valve cover and oil filter housing gaskets as standard. For a full breakdown of market rates, see our full reconditioned engine cost guide.
Labour Guide
Fitting an M112 engine typically takes 10-14 hours at £65-£85/hr (independent) - confirm exact labour when comparing quotes.
Price Factors
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Common Problems
Mercedes-Benz M112 Engine Problems - What Actually Fails
Every engine has its weak points. Here are the known issues with the M112, based on real-world data and verified failure patterns.
Verified issue focus: Crankshaft position sensor (CPS) failure and balance shaft gear wear.
1. Crankshaft Position Sensor (CPS) Failure - All variants
1. Crankshaft Position Sensor (CPS) Failure - All variants
Typical onset:
80,000-150,000 miles
What happens:
The CPS is located at the rear of the engine block, near the firewall, where it is exposed to extreme heat cycles. The internal wiring degrades, causing the sensor to fail when the engine is hot. This results in sudden stalling, a no-start condition, or rough running until the engine cools down.
Repair vs replace:
Replacing the CPS is a relatively inexpensive and straightforward repair, though access is tight. It is highly recommended to replace the sensor proactively during any major engine service.
Read more about this issue
2. Balance Shaft Gear Wear - Early variants
2. Balance Shaft Gear Wear - Early variants
Typical onset:
100,000-150,000 miles
What happens:
The balance shafts, designed to smooth out V6 vibrations, are driven by small gears that can wear or shear over time, particularly on early production models. This triggers crankshaft position sensor error codes, causes a rough idle, and in severe cases, broken gear fragments can jam the oil pump or timing chain.
Repair vs replace:
If caught early, replacing the balance shaft assembly and gears is a known, albeit labour-intensive, repair. If the oil pump or timing has been compromised, a full reconditioned M112 unit is required.
Read more about this issue
3. Oil Leaks (Valve Cover, Oil Filter Housing, Rear Main) - All variants
3. Oil Leaks (Valve Cover, Oil Filter Housing, Rear Main) - All variants
Typical onset:
80,000+ miles
What happens:
The M112 features several gaskets that harden and shrink with age and heat cycles. The most common leak points are the valley cover gasket (leaking oil into the spark plug wells), the oil filter housing gasket, and the rear main crankshaft seal.
Repair vs replace:
These are routine maintenance items. Replacing the gaskets and seals is relatively inexpensive in terms of parts, though the rear main seal requires significant labour to access.
Read more about this issue
The M112 is widely regarded as one of the most durable and smoothest V6 engines Mercedes ever produced. Post-2000 units with revised balance shaft gear materials and updated CPS wiring show significantly improved longevity, routinely exceeding 250,000 miles without major internal bottom-end issues .
Compare rebuilt M112 engine prices with the failure already addressed
Engine Variants
M112 Sub-Codes Explained - Which One Is in Your Car-
INTRO: The M112 family shares the same fundamental SOHC 18-valve V6 block architecture, but displacement and the presence of the Eaton supercharger (on AMG variants) vary significantly. Identifying your exact sub-code is mandatory, as fitting the wrong revision can lead to severe mechanical and ECU incompatibility. - Fitted to: C-Class W202 (C 240) - Key technical difference: The entry-level 2.4L variant, designed to meet specific tax-bracket displacement limits in several European markets, featuring port fuel injection and a focus on smooth, reliable daily driving. - Sub-code-specific failure note: Shares the family failure pattern above; no unique widespread defects beyond standard CPS and balance shaft wear. - Interchange note: Not a straight swap with larger displacement variants due to different engine mounts, wiring harnesses, and ECU mapping. - Fitted to: C-Class W202 (C 280), E-Class W210 (E 280) - Key technical difference: The volume-seller 2.8L variant, featuring a longer stroke for higher low-end torque, making it the preferred choice for the heavier W210 E-Class chassis. - Sub-code-specific failure note: Shares the family failure pattern above; early models are particularly susceptible to balance shaft gear wear. - Interchange note: Requires matching sump and accessory drives; passenger car variants are not directly interchangeable with commercial/off-road specs without modification. - Fitted to: E-Class W210 (E 320), CLK-Class W208 (CLK 320) - Key technical difference: The high-output naturally aspirated variant, featuring revised cylinder head casting for improved high-RPM airflow and updated HFM engine management. - Sub-code-specific failure note: Shares the family failure pattern above; the HFM throttle body is prone to internal potentiometer wear, causing idle surging. - Interchange note: Shares the core 3.2L architecture with other variants, but the engine mounts, wiring harness routing, and ECU mapping are specific to the W210/W208 chassis. - Fitted to: C-Class W203 (C 240 early), E-Class W211 (E 240) - Key technical difference: A transitional variant featuring updated engine management, electronic throttle body, and revised emissions hardware for the transition into the W203 and W211 era. - Sub-code-specific failure note: Shares the family failure pattern above; later models feature slightly improved balance shaft gear materials and updated CPS wiring. - Interchange note: Requires specific W203/W211 wiring harnesses and ECU calibration; not a direct drop-in for earlier W202/W210 chassis. - Fitted to: C-Class W203 (C 32 AMG), SLK-Class R170 (SLK 32 AMG) - Key technical difference: The legendary AMG variant, featuring an Eaton M112 supercharger, forged internals, upgraded cooling, and aggressive camshaft profiles to deliver sports-car performance. - Sub-code-specific failure note: Shares the family failure pattern above; supercharger coupler degradation and intercooler pump failures are the primary unique wear items. - Interchange note: Not interchangeable with naturally aspirated variants without swapping the supercharger, intake manifold, exhaust, and specific AMG ECU mapping.
The engine code is stamped on the right-hand side of the cylinder block, near the oil filter housing. It will also be listed on your V5C logbook under "Engine Capacity" or visible via a VIN decode. Not sure- Enter your registration above for instant confirmation.
Easily Confused
M104
the older 2.8L-3.2L inline-6 that the M112 replaced, sharing the same robust naturally aspirated philosophy but transitioning to a more compact, smoother 90-degree V6 architecture.
Alternative / Next-Gen Code
M272
the modern 3.0L-3.5L V6 that eventually replaced the M112 across the C-Class, E-Class, and S-Class range, introducing 4-valve-per-cylinder technology, variable valve timing, and improved emissions compliance.
Related JLR Variants
M113
the contemporary 4.3L-5.5L V8 that shared the same 90-degree V-angle architecture, SOHC 3-valve design, and transitional engine management, but in a larger configuration for flagship and high-performance applications.
Confirm the exact M112 fitment
The engine code is stamped on the right-hand side of the cylinder block, near the oil filter housing. It will also be listed on your V5C logbook under "Engine Capacity" or visible via a VIN decode. Not sure- Enter your registration above for instant confirmation.
Buying Guide
Buying a Replacement M112 Engine - What to Choose
Choosing the right replacement route depends on your budget, risk tolerance, and ownership goals. Here's a breakdown of your options.
Used:
A used M112 engine makes sense only if it comes with verifiable service history and documented proof of a recent balance shaft gear inspection/replacement and CPS replacement. Given the risk of balance shaft failure on early models, buying a used unit with unknown history is a significant financial risk.
Reconditioned:
A proper reconditioned M112 engine is the sweet spot for most buyers. A reputable rebuild will proactively address the common failure points by replacing the balance shaft assembly, fitting a new timing chain kit, replacing the CPS, and renewing all brittle valve cover and oil seals, giving the engine a fresh, reliable lease on life.
Rebuilt:
A full M112 engine rebuild is highly justified for classic W208 CLK 320 or R170 SLK 32 AMG restorations where originality, matching numbers, and maximum longevity are required. An upgraded rebuild should include line-boring the block, new pistons/rings, and a balanced crankshaft.
Supply & Fit Line:
Sourcing and fitting through our vetted network ensures your M112 engine is installed by specialists familiar with classic Mercedes V6 and Kompressor systems, backed by a nationwide warranty.
Vehicle Value Note:
Because the M112 is typically found in W202, W210, W203, W211, and R170 vehicles valued between £1,500 and £10,000+ (with low-mileage C32/SLK32 AMG models commanding significantly higher premiums), a full replacement is generally financially viable. However, if the lowest viable replacement cost exceeds approximately 60% of the vehicle's current market value, evaluate scrap value before committing .
Compare M112 Engine Prices Now
Related Engines
Engines Related to the Mercedes-Benz M112
Explore engines that are closely related to the Mercedes-Benz M112, including its predecessor, successor, and key family variants.
Predecessor
M104
the older 2.8L-3.2L inline-6 that the M112 replaced, sharing the same robust naturally aspirated philosophy but transitioning to a more compact, smoother 90-degree V6 architecture.
Successor
M272
the modern 3.0L-3.5L V6 that eventually replaced the M112 across the C-Class, E-Class, and S-Class range, introducing 4-valve-per-cylinder technology, variable valve timing, and improved emissions compliance.
Sibling
M113
the contemporary 4.3L-5.5L V8 that shared the same 90-degree V-angle architecture, SOHC 3-valve design, and transitional engine management, but in a larger configuration for flagship and high-performance applications.
FAQ
Mercedes-Benz M112Frequently Asked Questions
Question 1How much does a Mercedes M112 engine replacement cost-
A reconditioned Mercedes M112 engine typically costs between £1,800 and £3,000 for supply only . Fitted costs generally range from £2,500 to £4,000 depending on the specialist, while used units can be found from £600 but carry a high financial risk due to the engine's age and known balance shaft or CPS issues. Compare M112 engine replacement quotes today
Compare M112 quotesQuestion 2What is the most common failure on the M112 engine-
The most documented issues are crankshaft position sensor (CPS) failure, balance shaft gear wear on early variants, and oil leaks from the valve cover or oil filter housing. The CPS degrades from heat and causes sudden stalling, while worn balance shaft gears can trigger error codes or, in severe cases, jam the oil pump. Get quotes for a rebuilt M112 with these issues resolved
Compare M112 quotesQuestion 3Which Mercedes models use the M112 engine-
The M112 was fitted to the W202 and W203 C-Class (C 240, C 280, C 320, C 32 AMG), the W210 and W211 E-Class (E 240, E 280, E 320), the W208 and W209 CLK-Class (CLK 240, CLK 320), the R170 SLK-Class (SLK 320, SLK 32 AMG), and the W220 S-Class (S 320), serving as the definitive V6 petrol for these chassis between 1996 and 2005. Check your registration to confirm your exact M112 fitment
Compare M112 quotesQuestion 4Should I buy a used or reconditioned M112 engine-
A reconditioned M112 is strongly recommended over a used unit. A proper rebuild will proactively address the fatal flaws of age by replacing the balance shaft assembly and gears, fitting a new timing chain kit, replacing the CPS, and renewing all brittle valve cover and oil seals, whereas a used engine with unknown history risks immediate, labour-intensive electrical or bottom-end repairs. Compare reconditioned M112 engine prices from UK specialists
Compare M112 quotesQuestion 5What is the difference between M112.910, .920, .940, .950, and .960-
The M112.910 is the 2.4L entry-level variant, the .920 is the 2.8L volume-seller, the .940 is the 3.2L naturally aspirated high-output variant, the .950 is the updated 2.4L/2.6L transitional variant with electronic throttle, and the .960 is the legendary 3.2L supercharged (Kompressor) AMG variant. They share the same core V6 block, but the displacement, supercharger plumbing, engine mounts, and ECU mapping differ significantly. Enter your reg above to identify your exact M112 sub-code ═══════════════════════════════════════
Compare M112 quotesCompare Mercedes-Benz M112 Engine Prices Today
Vetted UK specialists who work on classic Mercedes V6 and Kompressor systems like the M112 every week Minimum 12-month warranty on every reconditioned and rebuilt M112 engine Nationwide delivery - supply-only or full supply & fit available across the UK Get a free, no-obligation comparison of M112 engine prices tailored to your exact vehicle. Our registration lookup confirms your fitment before any quotes are sent, ensuring you receive the correct unit with a replaced balance shaft assembly, new CPS, and verified gaskets. With reconditioned M112 engines starting from an estimated £1,800, comparing takes two minutes and could save you hundreds on labour and unexpected teardowns.
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Minimum 12-Month Warranty
Minimum 12-month warranty on reconditioned and rebuilt options
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