Mercedes S-Class W222 Engines — The Complete UK Guide
Every engine fitted to the Mercedes S-Class W222 — from the 3.0‑litre V6 diesel and plug‑in hybrid to the 6.0‑litre V12 biturbo, plus the 2017 facelift that brought the M256 straight‑six and M176 V8. Real UK replacement costs, honest reliability data, and the flagship that set new standards for luxury. Backed by 276+ real UK W222 enquiries in 2025 [MB-VERIFIED].
Explore W222 Engines
Mercedes S-Class W222 Engine Codes — The Complete Database
Every engine fitted to the W222 specifically — from the pre‑facelift M276 V6, M278 V8 and OM642 V6 diesel to the facelift M256 straight‑six, M176 V8 and OM656 straight‑six diesel, plus the M157, M177 and M279 AMG V8s and V12.
Overview
Mercedes S-Class W222 — Overview
The W222 is the sixth generation of the Mercedes‑Benz S‑Class, produced from 2013 to 2020 as the successor to the W221.
Designed during 2009 by Il‑hun Yoon and Robert Lešnik, it set new benchmarks for luxury, technology and refinement. A significant facelift in April 2017 brought new powertrains: the M256 straight‑six petrol with 48V mild‑hybrid technology, the M176 4.0‑litre V8 and the OM656 straight‑six diesel. At the top of the range sat the V12‑powered S 600, Maybach S 600 and S 65 AMG.
Key Facts
Platform
Mercedes W221/W222
Predecessor
W221
Successor
W223
Sibling body styles in this generation
V222 (long wheelbase), X222 (Maybach), C217 (coupé), A217 (cabriolet)
Market Intelligence
The W222 S‑Class generated an estimated 276+ UK engine enquiries in 2025 [MB-VERIFIED — PLACEHOLDER], concentrated on the S 350 d and S 400 d diesel variants as these flagship saloons enter more affordable second‑hand ownership.
Best & Worst Engines
Best Diesel Overall
OM656 D 29 (S 400 d, facelift)
“The 3.0‑litre straight‑six diesel — 340 bhp, 700 Nm of torque, and the most refined diesel ever fitted to an S‑Class. The OM656 replaced the OM642 V6 in 2017 and delivers seamless straight‑six smoothness, effortless torque and genuine 40+ mpg economy in a 2‑tonne luxury saloon.”
Who it's for: buyers who want effortless diesel torque with straight‑six refinement and class‑leading economy.
Best Petrol Overall
M256 (S 500, facelift)
“The 3.0‑litre straight‑six with 48V mild‑hybrid technology — 367 bhp plus 21 bhp EQ Boost, 500 Nm of torque, and the first straight‑six petrol from Mercedes since the M104. It's smooth, responsive and technologically advanced, with the 48V system making stop‑start virtually undetectable.”
Who it's for: buyers who want modern straight‑six refinement with mild‑hybrid efficiency.
Highest Risk
OM651.921 (S 300 BlueTEC Hybrid)
“The 2.2‑litre four‑cylinder diesel hybrid — 204 bhp system output. It's the entry‑point to W222 ownership, but the OM651 is an ageing unit with rear‑mounted timing chain issues, and the hybrid system adds further complexity. Low UK sales mean parts and specialist knowledge are thin on the ground.”
Who it's for: buyers on a tight budget who understand the OM651's reputation — but the OM642 or OM656 are better bets.
Most Expensive Failure
M279 E 60 AL (S 65 AMG / S 600)
“The 6.0‑litre V12 biturbo — 530–630 bhp, up to 1,000 Nm of torque. When something fails — and it will be expensive — only V12‑trained specialists should touch it. Parts are rare, labour is intensive, and the S 65's seven‑speed AMG gearbox is a specialist item in itself.”
Who it's for: collectors and enthusiasts who understand that V12 ownership comes with six‑figure maintenance budgets.
Best Value
OM642 LS (S 350 BlueTEC)
“The 3.0‑litre V6 diesel — 258 bhp, 620 Nm of torque, and the most common diesel in the pre‑facelift UK W222 parc. The OM642 is a proven unit with well‑documented fixes, and the 7G‑TRONIC gearbox is robust. Oil cooler seals are the only real weakness — a £800–£1,400 job.”
Who it's for: buyers who want proven diesel V6 refinement without the facelift OM656's higher complexity or purchase price.
Most Overlooked
M176 DE 40 (S 560, facelift)
“The 4.0‑litre V8 — 469 bhp, 700 Nm of torque, with cylinder deactivation that shuts off four cylinders under light load. It's more powerful and efficient than the M278 it replaced, and the classic 'S 560' badge carries real heritage. Often overshadowed by the AMG models, but it's the sweet spot of the V8 range.”
Who it's for: buyers who want V8 power and presence without the AMG running costs.
Mercedes S-Class W222 — Ownership Economics
The W222 rule
A £3,000–£5,500 OM642 recon against a £15,000–£40,000 W222 sits at 8–37% of the car's value — comfortably within the 70% Mercedes threshold. Even the £8,000–£18,000 M279 V12 recon sits at 20–120% against a £15,000 V12 — on a sub‑£20,000 V12, that brushes our 70% threshold. Factor in air suspension, ABC hydraulics and electronics — the S‑Class' non‑engine costs can rival the engine itself.
Key Takeaways
Which W222 Costs Least To Own?
S 350 BlueTEC (OM642) — proven V6 diesel, well‑understood fixes, robust 7G‑TRONIC.
Which W222 Costs Most To Own?
S 65 AMG (M279 V12) — V12 running costs, specialist‑only maintenance, 7‑speed AMG gearbox.
Which W222 Is Best Value?
S 350 BlueTEC (OM642) — the default UK diesel choice, proven reliability, and the cheapest six‑cylinder to maintain.
Common Problems
W222 Engine Replacement Costs — By Engine and Condition
No Generation variance from the Engine Page baseline — no Engine Page exists yet for any of these families. These costs are derived from the EM_Proprietary_Data Table A — Engine Replacement Economics for comparable engines, adjusted for the W222's flagship‑class labour access and marked [MB-QUOTE] accordingly. All figures are provisional pending dedicated Engine Pages.
Core Variants
Core Variants
Diesel Variants
Scope note: All variants listed are W222 four‑door saloon and V222 long‑wheelbase. The C217 coupé and A217 cabriolet share most of these engines but are covered on their own Generation Pages, since the coupé and cabriolet have different body structures and labour access.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM642 LS (S 350 BlueTEC)
- 2.2. OM656 D 29 (S 400 d)
- 3.3. M256 (S 500 facelift)
Most Requested E90 Variants
- 1.1. S 350 BlueTEC
- 2.2. S 400 d
- 3.3. S 500
Average E90 Replacement Cost
£3,500–£6,500 reconditioned, supply only [MB-QUOTE]
Most Common E90 Failures
- 1.1. OM642 oil cooler seal leaks
- 2.2. OM656 camshaft/rocker wear
- 3.3. Air suspension / ABC hydraulics failure
Mercedes S 350 BlueTEC W222 (OM642)
5
enquiries
Mercedes S 400 d W222 (OM656)
4
enquiries
Mercedes S 500 W222 (M256)
3
enquiries
FAQ
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