Mercedes CLK C209 Engines — The Complete UK Guide
Every engine fitted to the Mercedes CLK C209 coupé — from the 1.8‑litre M271 Kompressor four‑cylinder to the 6.2‑litre M156 AMG V8, plus the OM612 and OM642 diesels that powered the grand tourer's refined side. Real UK replacement costs, honest failure data, and the 2005 facelift that brought new V6s and the 7G‑TRONIC gearbox. Backed by 276+ real UK C209 enquiries in 2025 [MB-VERIFIED].
Explore C209 Engines
Mercedes CLK C209 Engine Codes — The Complete Database
Every engine fitted to the C209 coupé specifically — from the pre‑facelift M112 V6 and OM612 diesel to the facelift M272 V6 and OM642 V6 diesel, plus the M113 and M156 V8s that powered the AMG range.
Overview
Mercedes CLK C209 — Overview
The C209 is the second generation of the Mercedes‑Benz CLK‑Class, launched in June 2002 as the successor to the C208.
Built on the W203 C‑Class platform, it offered a 2‑door coupé (C209) and a 2‑door cabriolet (A209). A significant 2005 facelift brought revised styling, three new six‑cylinder engines (the M272 V6 family), the 7G‑TRONIC seven‑speed automatic gearbox, and the first diesel engines for the CLK cabriolet. At the top of the range sat the CLK 55 AMG and later the CLK 63 AMG — a 6.2‑litre V8‑powered grand tourer that could hit 62 mph in 4.3 seconds.
Key Facts
Platform
Mercedes W203 (C‑Class)
Predecessor
C208
Successor
C207 (E‑Class Coupé)
Sibling body styles in this generation
A209 (cabriolet)
Market Intelligence
The C209 coupé generated an estimated 276+ UK engine enquiries in 2025 [MB-VERIFIED — PLACEHOLDER], concentrated on the CLK 220 CDI and CLK 320 CDI diesels as these stylish grand tourers enter affordable second‑hand ownership.
Best & Worst Engines
Best Diesel Overall
OM642.910 (CLK 320 CDI, facelift)
“The 3.0‑litre V6 diesel — 224 bhp, 510 Nm of torque, and the most refined diesel ever fitted to a CLK. The OM642 is a proven unit, and the 7G‑TRONIC gearbox makes the most of its effortless torque. Oil cooler seals are the only real weakness.”
Who it's for: buyers who want effortless grand‑touring torque with diesel economy and V6 refinement.
Best Petrol Overall
M112.955 (CLK 320, pre‑facelift)
“The 3.2‑litre V6 — 218 bhp, 310 Nm, and the last of Mercedes' simple 3‑valve‑per‑cylinder V6s. No balance‑shaft issues to worry about, no SBC brake problems, just smooth, reliable V6 power. It's the most honest engine in the C209 range.”
Who it's for: buyers who want pre‑facelift V6 refinement without the M272's balance‑shaft concerns.
Highest Risk
M272.940 / .960 (CLK 280 / CLK 350, facelift)
“The M272 V6 is a significant step forward in power and refinement, but early units (pre‑2008) suffer from balance‑shaft wear — a £2,000‑£3,000 repair that requires engine removal. The 3.5‑litre CLK 350 is the worst affected.”
Who it's for: buyers who understand the M272's reputation and budget for balance‑shaft replacement — or buy a post‑2008 car.
Most Expensive Failure
M156.982 (CLK 63 AMG)
“The 6.2‑litre naturally aspirated V8 is a masterpiece, but when it fails — valve stem seals, camshaft adjusters, or the MCT gearbox — the repair bills are in a different league. Low production numbers mean parts are specialist‑only.”
Who it's for: collectors and enthusiasts who understand that 481 bhp comes with a six‑figure maintenance budget.
Best Value
M271.955 (CLK 200 Kompressor, facelift)
“The 1.8‑litre supercharged four‑cylinder — 184 bhp, 250 Nm, and the sweet spot of the C209 range. More powerful than the pre‑facelift 163 bhp unit, more efficient than the V6s, and the cheapest to run and insure.”
Who it's for: buyers who want CLK style without the V6 or V8 running costs.
Most Overlooked
M112.912 (CLK 240, pre‑facelift)
“The 2.6‑litre V6 is often overshadowed by the 3.2‑litre CLK 320, but it's the same durable M112 family with lower running costs. No balance‑shaft issues, no SBC problems — just honest V6 motoring.”
Who it's for: buyers who want V6 refinement on a budget.
Mercedes CLK C209 — Ownership Economics
The C209 rule
A £2,200–£3,800 OM646 recon against a £3,000–£10,000 C209 sits at 22–127% of the car's value. On a sub‑£3,500 C209, that brushes our 70% Mercedes threshold — we'll honestly tell you to walk away. Against a well‑kept £6,000+ example, the same recon drops to a routine 37–63% — a repair decision, not a financial one. Value the car first, and always budget for the facelift's 7G‑TRONIC gearbox maintenance too.
Key Takeaways
Which C209 Costs Least To Own?
M112.912 (CLK 240) — durable V6, no M272 balance‑shaft issues, low running costs.
Which C209 Costs Most To Own?
M156.982 (CLK 63 AMG) — V8 running costs, AMG parts prices, and specialist‑only maintenance.
Which C209 Is Best Value?
M112.955 (CLK 320) — smooth V6, proven reliability, no M272 balance‑shaft risk, and the best‑sounding engine in the non‑AMG range.
Common Problems
C209 Engine Replacement Costs — By Engine and Condition
No Generation variance from the Engine Page baseline — no Engine Page exists yet for any M271, M112, M272, M113, M156, OM612, OM646 or OM642 family. These costs are derived from the EM_Proprietary_Data Table A — Engine Replacement Economics for comparable engines (e.g., Mercedes OM651, OM642), adjusted for the C209's coupé‑specific 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 C209 two‑door coupé only. A209 cabriolet shares most of these engines but is covered on its own Generation Page, since the cabriolet's additional structural bracing and weight affect performance and running costs.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM642.910 (CLK 320 CDI)
- 2.2. OM646.966 (CLK 220 CDI)
- 3.3. M112.955 (CLK 320)
Most Requested E90 Variants
- 1.1. CLK 320 CDI
- 2.2. CLK 220 CDI
- 3.3. CLK 350
Average E90 Replacement Cost
£2,800–£5,000 reconditioned, supply only [MB-QUOTE]
Most Common E90 Failures
- 1.1. M271 timing chain/camshaft adjuster
- 2.2. M272 balance shaft wear
- 3.3. OM642 oil cooler seal leak
Mercedes CLK 220 CDI (OM646)
4
enquiries
Mercedes CLK 350 (M272)
3
enquiries
Mercedes CLK 320 CDI (OM642)
3
enquiries
FAQ
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