Mercedes‑Benz S‑Class W221 Engines — The Complete UK Guide
Every engine fitted to the W221 saloon — from the 3.0‑litre OM642 diesel to the 6.0‑litre M275 V12 in the S 65 AMG. Real UK replacement costs, honest reliability data, and the S‑Class ownership realities that define this generation. Backed by real UK W221 enquiries in 2025 [MB‑VERIFIED].
Explore W221 Engines
Mercedes‑Benz S‑Class W221 Engine Codes — The Complete Database
Every engine fitted to the W221 saloon specifically — spanning the pre‑facelift (2005–2009) and facelift (2009–2013) eras.
Overview
Mercedes‑Benz S‑Class W221 — Overview
The W221 is the fifth generation of the Mercedes‑Benz S‑Class, produced from August 2005 until June 2013.
It succeeded the W220 and was designed as the flagship of the Mercedes range — the "S‑Class among S‑Classes" — with a larger body than its predecessor, significantly more interior space, and a range of V6, V8 and V12 engines. A major 2009 facelift brought the S 400 Hybrid (the first production hybrid from Mercedes), the M278 twin‑turbo V8 replacing the M273, and the OM642 BlueTEC diesel with reduced emissions.
Key Facts
Platform
Mercedes‑Benz W221
Predecessor
W220
Successor
W222
Sibling body styles in this generation
C216 CL‑Class (coupé)
Market Intelligence
The S‑Class range (W221/W222 combined) generated real UK engine enquiries in 2025 [MB‑VERIFIED], with the OM642 diesel and AMG V8s commanding the strongest specialist interest.
Best & Worst Engines
Best Diesel Overall
OM642 3.0‑litre V6 diesel (S 350 BlueTEC, 258hp)
“The proven 3.0‑litre V6 turbo diesel that powered the W221 from 2010 onwards — 258hp, 620Nm of torque, and a documented reputation for longevity. Oil cooler seals are the main watchpoint, but the engine itself is robust and well‑supported across the Mercedes range.”
Who it's for: buyers who want effortless V6 diesel torque with S‑Class refinement.
Best Petrol Overall
M278 4.7‑litre V8 twin‑turbo (S 500, 435hp)
“The facelift‑era twin‑turbo V8 delivers 435hp and 700Nm from a 4.7‑litre V8 — smooth, effortless, and a genuine step forward from the M273 it replaced. It's the sensible performance choice in the W221 petrol range.”
Who it's for: buyers who want V8 performance with modern efficiency.
Highest Risk
M272 3.5‑litre V6 (S 350, pre‑facelift)
“The pre‑facelift M272 V6 has a well‑documented balance shaft sprocket wear issue — the sprocket teeth can wear prematurely, causing the timing chain to jump. Early detection is critical; a full rebuild is a four‑figure bill.”
Who it's for: buyers who understand the risk and are prepared for potential balance shaft work.
Most Expensive Failure
M275 6.0‑litre V12 twin‑turbo (S 65 AMG, 630hp)
“The pinnacle of the W221 range — a hand‑built V12 with 630hp and 1000Nm. Coil packs, ignition modules, and cooling system failures are documented on higher‑mileage examples. A full recon is a five‑figure bill, and parts availability is a consideration.”
Who it's for: collectors and V12 enthusiasts with deep pockets and a trusted specialist.
Best Value
OM642 3.0‑litre V6 diesel (S 320 CDI, 235hp)
“The pre‑facelift OM642 diesel offers the same robust V6 as the S 350 BlueTEC, but at a lower purchase price. 235hp and 540Nm deliver effortless S‑Class performance, and the engine is proven across the Mercedes range.”
Who it's for: buyers who want S‑Class luxury on a tighter budget.
Most Overlooked
M156 6.2‑litre V8 (S 63 AMG, pre‑facelift, 525hp)
“The pre‑facelift S 63 AMG with the M156 6.2‑litre naturally‑aspirated V8 is often overlooked in favour of the facelift M157 twin‑turbo — but the M156 is the last of the great naturally‑aspirated AMG V8s, with 525hp and a soundtrack that no turbocharged engine can match.”
Who it's for: AMG enthusiasts who value character over outright pace.
Mercedes‑Benz S‑Class W221 — Ownership Economics
The W221 rule
A £3,200–£5,500 OM642 recon against a £6,000–£15,000 W221 sits at 21–92% of the car's value — on a high‑mileage £6,000 example, that brushes the 70% Mercedes‑Benz threshold. Against a well‑kept £12,000+ example, the same recon drops to 27–46% — a routine repair decision, not a financial one. However, a £12,000–£18,000 M275 V12 recon against a £10,000 W221 is 120–180% — on a high‑mileage V12, that's the point where you seriously question whether the car is economically viable. Value the car and its service history first.
Common Problems
W221 Engine Replacement Costs — By Engine and Condition
Core Variants
Core Variants
Market Intelligence
Most Requested E90 Engines (2025)
Most Requested E90 Variants
Average E90 Replacement Cost
Most Common E90 Failures
FAQ
Why UK Mercedes‑Benz S‑Class W221 Owners Trust MercedesEngines.uk
Trusted W221 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real W221 owners, as part of the Engine Finders network.
Compare W221 Engine Replacement Companies
see prices, warranty terms and supply‑and‑fit options side‑by‑side before you commit.
UK Engine Replacement Services for W221
covering every variant from S 250 CDI to S 65 AMG, with supply‑only or full supply‑and‑fit available nationwide.
Find the best Mercedes‑Benz S‑Class W221 engine replacement UK drivers rely on. Compare real prices from trusted specialists on EnginesMarket today and get back on the road with confidence.
