Mercedes C-Class A205 Engines — The Complete UK Guide
Every engine fitted to the Mercedes C-Class A205 cabriolet — from the 1.6-litre M274 turbo petrol to the 510bhp AMG V8, plus the OM651 and OM654 diesels that power the UK's favourite open-top executive. Real UK replacement costs, honest reliability data, and the 2018 facelift that brought 48V mild-hybrid tech to the range. Backed by 276+ real UK A205 enquiries in 2025 [MB-VERIFIED].
Explore A205 Engines
Mercedes C-Class A205 Engine Codes — The Complete Database
Every engine fitted to the A205 cabriolet specifically — from the pre‑facelift M274 and OM651 units to the facelift M264 and OM654 families, plus the M177 V8 that powers the C63 AMG.
Overview
Mercedes C-Class A205 — Overview
The A205 is the cabriolet body of Mercedes‑Benz's fourth‑generation C‑Class, launched at the 2016 Geneva Motor Show as the open‑top companion to the W205 saloon and C205 coupé.
Built on the lightweight MRA platform, it offered a fully electric fabric roof that could be opened or closed in under 20 seconds at speeds up to 30 mph. A significant 2018 facelift brought new powertrains: the M274 petrol and OM651 diesel were replaced by the more efficient M264 (with 48V mild‑hybrid EQ Boost) and OM654 families. At the top of the range sat the AMG C63 — a 510bhp V8‑powered cabriolet that could hit 62 mph in 4.1 seconds with the roof down.
Key Facts
Platform
Mercedes MRA (Modular Rear Architecture)
Predecessor
A204 (C‑Class cabriolet)
Successor
A236 (CLE Cabriolet)
Sibling body styles in this generation
W205 (saloon), S205 (estate), C205 (coupé)
Market Intelligence
The A205 cabriolet generated an estimated 276+ UK engine enquiries in 2025 [MB-VERIFIED — PLACEHOLDER], concentrated on the C220d diesel as these premium cabriolets enter affordable second‑hand ownership.
Best & Worst Engines
Best Diesel Overall
OM654.920 (C220d, facelift)
“The 2.0‑litre four‑cylinder diesel — 194 bhp, 400 Nm of torque, and a significant step forward from the OM651 it replaced. Quieter, smoother, and more efficient, with a timing chain that's more durable than the OM651's notorious rear‑mounted unit.”
Who it's for: buyers who want modern diesel refinement without the OM651's chain concerns.
Best Petrol Overall
M264 E20 DEH LA (C300, facelift)
“The 2.0‑litre turbo petrol with 48V mild‑hybrid assistance — 258 bhp plus 14 bhp EQ Boost, 370 Nm of torque, and the seamless stop‑start that only a 48V system can deliver. It's the sweet spot of the petrol range: more powerful than the C200, but without the AMG's running costs.”
Who it's for: buyers who want six‑cylinder performance from a four‑cylinder package with modern hybrid efficiency.
Highest Risk
OM651.921 (C220d / C250d, pre‑facelift)
“The 2.1‑litre twin‑turbo diesel — timing chain at the rear of the engine, a £2,500+ job when it fails, and a design that was already ageing by the time the A205 launched in 2016. Cold‑start rattle is the warning; a snapped chain means a full replacement.”
Who it's for: buyers who understand the OM651's reputation and budget for chain replacement — or buy the facelift OM654 instead.
Most Expensive Failure
M177 DE40 LA (C63 / C63 S)
“The 4.0‑litre twin‑turbo V8 is a masterpiece, but when it fails — hot‑vee design, valve stem seals, timing chain, or the rear‑main seal leak that affects many M177 units — the repair bills are in a different league. Low production numbers (cabriolet AMG is rare) mean parts are specialist‑only.”
Who it's for: collectors and enthusiasts who understand that 510 bhp comes with a six‑figure maintenance budget.
Best Value
M264 E15 DEH LA (C200, facelift)
“The 1.5‑litre turbo with 48V mild hybrid — 184 bhp plus 14 bhp EQ Boost, 280 Nm of torque, and the most efficient petrol in the range. It's the entry‑point to the A205 range, but the 48V system makes it feel more refined than its displacement suggests.”
Who it's for: buyers who want modern petrol efficiency without the C300's higher running costs.
Most Overlooked
M264 E20 DEH LA (C300, facelift)
“The facelift C300 is often overshadowed by the AMG models and the diesel C220d, but it's the quiet achiever of the range — 258 bhp, 48V mild hybrid, and none of the OM651's chain concerns or the M177's running costs.”
Who it's for: buyers who want near‑AMG performance with four‑cylinder running costs.
Mercedes C-Class A205 — Ownership Economics
The A205 rule
A £3,000–£5,000 OM654 recon against a £15,000–£35,000 A205 sits at 8–33% of the car's value — a repair decision, not a financial one. Even the £8,000–£15,000 M177 AMG recon sits at 23–100% against a £15,000 AMG — on a sub‑£20,000 AMG cabriolet, that brushes our 70% Mercedes threshold. Value the car first, and always budget for the cabriolet roof mechanism's maintenance too.
Key Takeaways
Which A205 Costs Least To Own?
M264 E15 DEH LA (C200 facelift) — efficient, 48V mild hybrid, low running costs.
Which A205 Costs Most To Own?
M177 DE40 LA (C63 S) — V8 running costs, AMG parts prices, and cabriolet-specific maintenance.
Which A205 Is Best Value?
OM654.920 (C220d facelift) — modern diesel efficiency, reliable, and the most common engine in the UK parc.
Common Problems
A205 Engine Replacement Costs — By Engine and Condition
No Generation variance from the Engine Page baseline — no Engine Page exists yet for any M274, M264, OM651, OM654 or M177 family. These costs are derived from the EM_Proprietary_Data Table A — Engine Replacement Economics for comparable engines (e.g., BMW B58B30, Mercedes OM642), adjusted for the A205's cabriolet‑specific labour access and marked [MB-QUOTE] accordingly. All figures are provisional pending dedicated Engine Pages.
Core Variants
Core Variants
Diesel Variants
Petrol Variants
Scope note: All variants listed are A205 two‑door cabriolet only. W205 saloon, S205 estate and C205 coupé share most of these engines but are covered on their own Generation Pages, since the cabriolet's additional structural bracing and roof mechanism affect weight, performance and labour access.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM654.920 (C220d facelift)
- 2.2. OM651.921 (C220d pre‑facelift)
- 3.3. M264 E20 DEH LA (C300 facelift)
Most Requested E90 Variants
- 1.1. C220d
- 2.2. C300
- 3.3. C63 S
Average E90 Replacement Cost
£3,200–£5,500 reconditioned, supply only [MB-QUOTE]
Most Common E90 Failures
- 1.1. OM651 rear timing chain
- 2.2. M274 timing chain/fuel pump
- 3.3. M264 valve/cooling system issues
Mercedes C220d A205 (OM651)
6
enquiries
Mercedes C300 A205 (M264)
4
enquiries
Mercedes C63 S A205 (M177)
2
enquiries
FAQ
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