Mercedes C-Class S204 Engines — The Complete UK Guide
Every engine fitted to the C-Class Estate — from the supercharged M271 four-cylinder to the V6 M272 and the OM651 diesel that redefined refinement. Real UK costs, honest reliability data, and the engine choices that defined the third‑gen C‑Class estate. Backed by 1,250+ real UK enquiries in 2025 [MB‑VERIFIED].
Explore S204 Engines
Mercedes C-Class S204 Engine Codes — The Complete Database
Every engine fitted to the S204 estate specifically — including the pre‑ and post‑facelift engine changes that transformed this generation.
Overview
Mercedes C-Class S204 — Overview
The S204 is the estate version of the third‑generation Mercedes‑Benz C‑Class (W204), launched in August 2007 as the successor to the S203 estate.
Built on the same platform as the W204 saloon, it shared the full engine lineup — from the supercharged M271 four‑cylinder petrols to the V6 M272 and the OM651 diesel family that redefined the C‑Class driving experience. A significant facelift arrived in 2011, bringing new engines including the M276 V6 petrol and OM642 V6 diesel.
Key Facts
Platform
Mercedes W204 (shared with W204 saloon, C204 coupé)
Predecessor
S203 (2001–2007)
Successor
S205 (2014–2021)
Sibling body styles in this generation
W204 (saloon), C204 (coupé)
Market Intelligence
The S204 C‑Class estate generated 1,250+ real UK engine enquiries in 2025 [MB‑VERIFIED], concentrated on the OM651 diesel as the most‑requested powertrain.
Best & Worst Engines
Best Diesel Overall
OM651.911 (C220 CDI/C250 CDI)
“Mercedes' own 2.1‑litre diesel, introduced in 2008, replaced the ageing OM646 with a lighter, more efficient design. It's the pick of the S204 range — smooth, torquey, and backed by a strong reliability record when serviced properly.”
Who it's for: buyers who want a modern, efficient diesel without the older engine's compromises.
Best Petrol Overall
M276.957 (C350, facelift)
“Mercedes' 3.5‑litre V6, introduced with the 2011 facelift, replaced the M272 with a more refined and reliable unit. It delivers 306 bhp with a silky character and strong torque.”
Who it's for: buyers who want genuine V6 performance from a family estate.
Highest Risk
M271.950/820/860 (C180/C200/C250 CGI)
“The M271 four‑cylinder petrol is known for timing chain stretch and tensioner failure — a problem that can lead to catastrophic engine damage if ignored. The EVO versions (820/860) improved the design but didn't eliminate the risk entirely.”
Who it's for: buyers on a budget who prioritise low running costs over long‑term reliability.
Most Expensive Failure
OM642.834 (C350 CDI) — oil cooler seal leak
“The V6 diesel's oil cooler seals are prone to failure, leaking oil into the V of the engine. Repair requires significant disassembly and can be costly if caught late.”
Who it's for: buyers who want the power of a V6 diesel but can afford the premium maintenance.
Best Value
OM651.911 (C220 CDI)
“The mid‑range diesel offers the best balance of performance (170 bhp), economy (up to 60 mpg), and reliability. It's the sweet spot in the S204 range.”
Who it's for: fleet buyers and high‑mileage drivers.
Most Overlooked
M272.947 (C300)
“The 3.0‑litre V6 petrol offers 231 bhp with a smooth, characterful delivery. It's often overlooked in favour of the diesels but offers a genuinely rewarding driving experience with fewer of the M271's timing chain concerns.”
Who it's for: enthusiasts who want a six‑cylinder estate without the running costs of the C350.
Mercedes C-Class S204 — Ownership Economics
The S204 rule
A £2,800–£4,800 OM651 recon against a £4,000–£12,000 S204 sits at 23–120% of the car's value. On a sub‑£5,000 S204, that brushes our 70% Mercedes threshold — we'll honestly tell you to walk away. Against a well‑kept £8,000+ example, the same recon drops to a routine 35–60% — a repair decision, not a financial one. Value the car first.
Key Takeaways
Which S204 Costs Least To Own?
C220 CDI (OM651) — best balance of economy and reliability.
Which S204 Costs Most To Own?
C350 CDI (OM642) — V6 diesel running costs add up.
Which S204 Is Best Value?
C220 CDI (OM651) — the sweet spot in the range.
Common Problems
S204 Engine Replacement Costs — By Engine and Condition
No Generation variance from the Model Page's baseline figures — the S204 shares its engine bay with the W204 saloon, so labour times and costs are consistent across the range. Costs are inherited directly per the Authority Model, with no divergence note required.
Core Variants
Core Variants
Scope note: All variants listed are S204 estate only. The W204 saloon and C204 coupé share most of these engines but are covered on their own Generation Pages, since fitment and labour access vary slightly by body style.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM651 (2.1 diesel) — most‑requested across the Mercedes range [MB‑VERIFIED]
- 2.2. M272/M276 (V6 petrol) — strong demand for performance estates
- 3.3. M271 (1.8 petrol) — popular entry‑level choice
Most Requested E90 Variants
- 1.1. C220 CDI
- 2.2. C350 (V6)
- 3.3. C200 CGI
Average E90 Replacement Cost
£1,800–£6,500 supply only [MB‑QUOTE]
Most Common E90 Failures
- 1.1. M271 timing chain stretch
- 2.2. OM651 injector seal leaks (Black Death)
- 3.3. OM642 oil cooler seal leaks
Mercedes C220 CDI S204 (OM651)
6
enquiries
Mercedes C350 S204 (M272)
4
enquiries
Mercedes C200 CGI S204 (M271)
3
enquiries
FAQ
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