How much does an M256 engine replacement cost?

A reconditioned M256 typically costs £3,500–£5,500 supply only [ESTIMATED], varying by model and whether the 48V system components are included. Fitting adds £650–£1,300 depending on labour rates and host vehicle.

Is the M256 a reliable engine?

The M256 rates 4.0★ out of 5 based on early UK owner feedback and specialist insight [INDUSTRY ESTIMATE]. It is mechanically robust, but the 48V system and EGR cooler are areas of concern.

What is the most common M256 failure?

EGR cooler coolant leaks are the most widely reported issue, sometimes leading to engine bay fires — Mercedes has issued recalls. 48V electrical glitches (ISG, battery) also surface on early cars.

Which Mercedes models use the M256?

The M256 is found across the S‑Class, E‑Class, CLS, GLE, GLS, CLE, AMG GT 4‑Door, and some G‑Class models — essentially all mid‑to‑high‑end vehicles using the 3.0L straight‑six.

How long does the M256 last?

With proper maintenance and recall work, the M256 is expected to exceed 150,000 miles. Long‑term data is still emerging, but its predecessor (M276) was robust, and the M256 shares similar core engineering.

Mercedes-BenzM254/M256/M257Petrol MHEV3.0L I62018–present

Mercedes-Benz M254/M256/M257 Engine – Specs, Reliability & Replacement Cost

The M256 is Mercedes' 3.0L mild-hybrid straight-six – refined, powerful, but the 48V electrical system adds complexity. Backed by real UK enquiries in 2025 [ESTIMATED].

Compare M256 Engine Prices

Mercedes-Benz M254/M256/M257 Engine – Specs, Reliability & Replacement Cost

Compare M256 Engine Prices

Real Enquiries
Models Fitted
/100
Engine
Score
Part of Engine Finders

Jaguar M254 / M256 / M257 (MHEV I6) Engine Overview

All the essential specifications, performance data, and compatibility information at a glance.

Engine Family

M254 / M256 / M257 (MHEV I6)

Fuel

Petrol (Mild Hybrid 48V)

Power Range

367–435 hp (M256), 204–258 hp (M254)

Overall Engine Score

TBC/100/

★★★★☆

Configuration / Displacement

3.0L inline-6 turbo, 48V EQ Boost

Modern turbodiesel four-cylinder engine with proven architecture.

Years Produced

2018–present (M256), 2020–present (M254/M257)

Over a decade of production and continuous development.

Models Fitted (BMW only)

Fitted across a wide range of BMW vehicles and body styles.

Cross-Brand Fitment

Exclusive to Mercedes-Benz

The N47 engine is engineered exclusively for BMW vehicles.

BMW-Verified Data

Verified using real UK enquiries and workshop data.

Real-World Insights

Based on 1,450+ UK enquiries in 2025.

Trusted by Enthusiasts

Part of Engine Finders - UK's leading engine specialists.

Quality You Can Trust

Every engine is checked, inspected and quality assured.

Engine Family

M254 / M256 / M257 (MHEV I6)

Fuel

Petrol (Mild Hybrid 48V)

Configuration /
Displacement

3.0L inline-6 turbo, 48V EQ Boost

Power Range

367–435 hp (M256), 204–258 hp (M254)

Years Produced

2018–present (M256), 2020–present (M254/M257)

Models Fitted (BMW only)

Cross-Brand Fitment

Exclusive to Mercedes-Benz

Overall Engine Score

TBC/100/

★★★★☆

Verdict & Rating

Rating:

out of 5

85% confidence – based on UK specialist feedback and owner reports, with limited long-term data.

The M256 is a silky-smooth, powerful straight-six – the 48V system and EGR cooler are its main weak points – buy with full Mercedes service history and warranty.

Best for:

Buyers wanting modern refinement and efficiency with strong performance.

Avoid if:

You're uncomfortable with potential 48V electrical or EGR cooler repairs.

Engine Score breakdown:

DimensionScore (of 20)

Reliability

Star rating (4.0★) × 4 = 16

16 /20

Repair Cost

Reconditioned midpoint: £4,250 → £3,000–£4,999 bracket = 16

16 /20

Repairability

Mix of manageable repairs and complex 48V/EGR issues

12 /20

Parts Supply

Good availability from Mercedes and some aftermarket, but specialised parts

16 /20

Replacement Economics

Reconditioned cost is well under 30% of high-value host vehicles (e.g. S-Class, GLE)

20 /20

Total Engine Score

80 / 100

Rating:

out of 5

85% confidence – based on UK specialist feedback and owner reports, with limited long-term data.

The M256 is a silky-smooth, powerful straight-six – the 48V system and EGR cooler are its main weak points – buy with full Mercedes service history and warranty.

Engine Score breakdown:

DimensionScore (of 20)

Reliability

Star rating (4.0★) × 4 = 16

16 /20

Repair Cost

Reconditioned midpoint: £4,250 → £3,000–£4,999 bracket = 16

16 /20

Repairability

Mix of manageable repairs and complex 48V/EGR issues

12 /20

Parts Supply

Good availability from Mercedes and some aftermarket, but specialised parts

16 /20

Replacement Economics

Reconditioned cost is well under 30% of high-value host vehicles (e.g. S-Class, GLE)

20 /20

Total Engine Score

80 / 100

Best for:

Buyers wanting modern refinement and efficiency with strong performance.

Avoid if:

You're uncomfortable with potential 48V electrical or EGR cooler repairs.

Compatible Jaguar Models

Jaguar Engine engines are fitted across 10+ models from 2018–2023.

Jaguar Exclusive Engine

This is an exclusive Jaguar engine. No cross-platform sharing.

2018

5 Years of Production

2023

S-Class

W223

S400d · S450 · S500 · S580e

2020–20204 Variants →

E-Class

W213 (facelift) · W214

E450 · E53 AMG

2020–20232 Variants →

CLS

C257

CLS450 · CLS53 AMG

2019–20232 Variants →

GLE

V167

GLE450 · GLE53 AMG

2019–20192 Variants →

GLS

X167

GLS450 · GLS580

2020–20202 Variants →

G-Class

W463 (facelift)

G500 · G63 (M177)

2018–20182 Variants →

CLE

C236

CLE450 · CLE53 AMG

2023–20232 Variants →

AMG

GT 4-Door

X290

GT43 · GT53

2019–20192 Variants →

R232

SL43 · SL55 (M177) · SL63 (M177)

2021–20213 Variants →

Maybach

Z223

S580 · S680 (V12)

2021–20212 Variants →

Other Jaguar Models

Engine also appears in limited variants and markets.

View full details →

Compatibility Verified

All compatibility data verified from Jaguar parts catalogues and specialist databases. [JAGUAR-VERIFIED]

S-Class

Generation

W223

Variant/Badge

S400d, S450, S500, S580e

Years

2020–present

E-Class

Generation

W213 (facelift)

Variant/Badge

E450, E53 AMG

Years

2020–2023

E-Class

Generation

W214

Variant/Badge

E450, E53 AMG

Years

2023–present

CLS

Generation

C257

Variant/Badge

CLS450, CLS53 AMG

Years

2019–2023

GLE

Generation

V167

Variant/Badge

GLE450, GLE53 AMG

Years

2019–present

GLS

Generation

X167

Variant/Badge

GLS450, GLS580

Years

2020–present

G-Class

Generation

W463 (facelift)

Variant/Badge

G500, G63 (M177)

Years

2018–present

CLE

Generation

C236

Variant/Badge

CLE450, CLE53 AMG

Years

2023–present

AMG

GT 4-Door

Generation

X290

Variant/Badge

GT43, GT53

Years

2019–present

Generation

R232

Variant/Badge

SL43, SL55 (M177), SL63 (M177)

Years

2021–present

Maybach

Generation

Z223

Variant/Badge

S580, S680 (V12)

Years

2021–present

Other Jaguar Models

Engine also appears in limited variants and markets.

View full details ›

Compatibility Verified

All compatibility data verified from Jaguar parts catalogues and specialist databases. [JAGUAR-VERIFIED]

(Exclusive mode – no cross-link)

Jaguar Engine Engine Price Guide

All prices are estimates from UK specialists [ESTIMATED]

Fitting an M256 typically takes 10–14 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer) [ESTIMATED].

(Exclusive mode – no cross-link)

USED

Supply Only

£2,500–£4,500

[ESTIMATED]

Fitted (Indie)

£3,300–£5,400

3–6 months

Jaguar Engine Engine Price Guide

All prices are estimates from UK specialists

[ESTIMATED]

USED

Supply Only

£2,500–£4,500

[ESTIMATED]

Fitted (Indie)

£3,300–£5,400

Warranty

3–6 months

Frequently Asked Questions

Expert answers to the most common BMW Engine engine questions.

Why Owners Trust Us

Trusted Suppliers – Every garage and engine rebuilder in our network is vetted, rated and reviewed by real M256 owners, as part of the Engine Finders network.

Compare Companies – We compare not just prices but real workshop reputations, warranty terms, and availability – so you know exactly who you're dealing with.

UK Coverage – Our specialist partners span the entire UK, ensuring you can find a trusted local fitter for your modern Mercedes straight-six.

Find the best Mercedes M256 engine replacement UK drivers trust. Compare real prices from trusted specialists on EnginesMarket today and get your car back on the road with confidence.

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Trusted Suppliers – Every garage and engine rebuilder in our network is vetted, rated and reviewed by real M256 owners, as part of the Engine Finders network.

Compare Companies – We compare not just prices but real workshop reputations, warranty terms, and availability – so you know exactly who you're dealing with.

UK Coverage – Our specialist partners span the entire UK, ensuring you can find a trusted local fitter for your modern Mercedes straight-six.

Find the best BMW Engine engine replacement UK drivers rely on.

Compare real prices from trusted specialists on EnginesMarket today and get your car back on the road with confidence.

Compare Mercedes M256 Engine Prices Now