Every Mercedes CLS generation — from the C219 that defined the four-door coupé to the modern C257. Full coverage of OM651 diesel reliability, OM642 V6 costs, M276 petrol timing chain history, and real UK replacement economics. Backed by 306+ genuine UK CLS engine enquiries in 2025 [MB-VERIFIED].
Explore CLS Engines306+ Enquiries (2025) [MB-VERIFIED]
3 Generations Covered
7+ Engine Codes
Part of Engine Finders
★★★★☆
⚠️ The CLS rule: generation is destiny — the same engine can be a £3,000–£5,500 repair on a £10,000 car or a trivial spend on a £45,000 car. Buy the newest generation you can afford, or accept the risk.
★★★★☆
OM654 — the modern 2.0-litre diesel with materially fewer failure reports than its predecessor; 520 UK enquiries across all models in 2025 [MB-VERIFIED].
M276 3.0 V6 petrol — timing chain stretch on earlier examples; still a well-understood repair but worth factoring into any pre-2016 CLS purchase.
CLS C218 (2014–2016 facelift) with OM654 — post-facelift electronics, the more dependable diesel, and values that have absorbed the steepest depreciation.
£3,000–£6,500 reconditioned supply-only [MB-QUOTE], depending on engine.
OM651 "Black Death" injector seal failure — the defining Mercedes diesel issue [MB-VERIFIED].
💎 Style Over Practicality — the CLS is the most design-led Mercedes saloon, and its ownership economics reflect that: buy on condition and generation, not badge.
One-line verdict:
The CLS is a design icon that demands you buy the newest generation you can afford — the same engine family that's a safe bet in a £45,000 C257 is a scrap-threshold risk in a £4,000 C219.
Generations
3 (C219, C218, C257)
Years Produced
2004–present
Engine Codes Tracked
7+ (OM651, OM642, OM654, M276, M157, M256)
Fuel Types
Diesel • Petrol
Most Enquired Engine (2025)
OM651 (1,250 enquiries across Mercedes models, of which 146+ CLS-specific [MB-VERIFIED])
Most Reliable
OM654 — modern 2.0 diesel, 520 UK enquiries [MB-VERIFIED]
Highest-Risk
M276 V6 petrol — timing chain stretch on earlier C218 examples
Typical Replacement Cost
£2,800–£6,500 reconditioned supply-only [MB-QUOTE]
Typical Host Value
£3,000–£45,000 depending on generation [THIRD-PARTY]
Overall Rating
★★★★☆
3.9/5
A perfect blend of performance, engineering excellence, and drivability.
Three generations of the four-door coupé that defined a segment — each with its own engine story, reliability profile, and ownership economics.
| Pre-2013 (E90/F30 early) | 2013-2015 (F30 pre-LCI) | 2016+ (F30 LCI / G20) | Our position | |
|---|---|---|---|---|
| Core diesel | The 3 Series we recommend for daily ownership | |||
| Core petrol |
Read the full comparison: CLS C218 vs C257
Every engine ever fitted to the Mercedes CLS — verified against manufacturer specifications, with real UK enquiry data and specialist cost ranges.
| Engine Code | Family | Fuel | Disp. | Power | Years | Gen. | Reliability | 2025 Enquiries | Avg. Recon Cost |
|---|---|---|---|---|---|---|---|---|---|
| OM651 | OM651 | Diesel | 2.1L | 170–204hp | 2011–2018 | C218 | ★★★★★ | 146 [MB-VERIFIED] | £2,800–£4,800 [MB-QUOTE] |
| OM642 | OM642 | Diesel | 3.0L V6 | 224–265hp | 2004–2015 | C219, C218 | ★★★★★ | 40+ [MB-VERIFIED] | £3,200–£5,500 [MB-QUOTE] |
| OM654 | OM654 | Diesel | 2.0L | 194–265hp | 2014–present | C218, C257 | ★★★★★ | 120 [MB-VERIFIED] | £3,000–£5,000 [MB-QUOTE] |
| M272 | M272 | Petrol | 3.5L V6 | 272hp | 2004–2011 | C219 | ★★★★★ | [PATTERN DATA] | £2,500–£4,500 [MB-QUOTE] |
| M276 | M276 | Petrol | 3.5L V6 | 306–333hp | 2011–2018 | C218 | ★★★★★ | 390 [MB-VERIFIED] | £3,800–£6,500 [MB-QUOTE] |
| M157 | M157 | Petrol | 5.5L V8 Biturbo | 525–557hp | 2011–2018 | C218 (CLS 63 AMG) | ★★★★★ | [PATTERN DATA] | £8,000–£14,000 [MB-QUOTE] |
| M256 | M256 | Petrol | 3.0L Straight-six | 367–435hp | 2018–present | C257 | ★★★★★ | [PATTERN DATA] | £5,000–£8,000 [MB-QUOTE] |
| M177 | M177 | Petrol | 4.0L V8 Biturbo | 612hp | 2018–present | C257 (AMG) | ★★★★★ | 370 [MB-VERIFIED] | £8,000–£14,000 [MB-QUOTE] |
Showing 8 of 8 engine codes
iAll enquiries are from 2025 (to date) and verified via our internal system. Recon costs are supply only and exclude fitting.
How we collect engine dataThe complete database of BMW 3 Series engine codes with real UK enquiry data, fitted models, and replacement cost insights.
Every figure below is powered by 24,650+ real UK owner enquiries in 2025. This is data you won't find anywhere else.
Enquiry volumes:
EM_Proprietary_Data_2025.txt [EM-VERIFIED]
Costs:
Table A - Engine Replacement Economics [EM-QUOTE]
Engine codes:
Cross-referenced from your existing data
Real UK failure patterns from our 2025 enquiry data — what goes wrong, at what mileage, and what it costs to fix.
01The defining Mercedes diesel issue and our #1 enquiry driver. Copper injector seals degrade, leaking combustion gases into a carbon "tar" that can weld the injector into the head if ignored. Most common on C218 pre-2014. £400–£1,200 seal repair; up to full engine replacement if neglected [MB-QUOTE].
Read more
02The V6 diesel's primary weak point across C219 and early C218 — an O-ring fails in the "V" of the engine, requiring significant disassembly to access. Labour-heavy rather than catastrophic. 880 UK-wide enquiries in 2025 [MB-VERIFIED]. £800–£1,500 repair [MB-QUOTE].
Read more
03Chain stretch on earlier C218 examples (2011–2014), plus carbon buildup on intake valves — well-understood and rarely catastrophic if caught early. 390 UK-wide enquiries in 2025 [MB-VERIFIED]. £1,500–£2,500 repair [MB-QUOTE].
Read more
04Unlike most engines, the OM651's chain sits at the transmission end — access requires separating the engine from the gearbox. Pre-2014 C218 units at highest risk. Cold-start rattle is the early warning. £600–£1,500 repair [MB-QUOTE].
Read more
05The AMG V8's most expensive non-engine failure — HPFP failure can dump fuel into the oil, thinning it and causing bottom-end damage if driven. £1,000–£1,800 repair; catch early [MB-QUOTE].
Read more
06OM654-specific — usually a NOx sensor or heater fault, software-manageable rather than mechanical. £400–£1,500 repair [MB-QUOTE]. Not a reason to avoid the engine, but budget for it.
Read moreCatastrophicstop driving, specialist inspection immediately
Immediatebook inspection now
Monitorbook inspection soon
Lowplan at next service
306++
Total Enquiries in 2025
[BMW-VERIFIED]
Most Enquired CLS Generation
Rising
Most Enquired CLS Engine
Stable
Average CLS Engine Replacement (Supply-Only)
Rising
CLS Enquiry Split: Diesel vs Petrol
Stable
Interesting insight: The C218 CLS (2011–2018) generates almost four times as many enquiries as the C219 and C257 combined — not because it's less reliable, but because it's the volume-generation CLS and sits in the depreciation sweet spot (£5,000–£18,000) where owners are most likely to seek replacement quotes rather than simply scrapping the car. The C257 is too new and too expensive to have entered the replacement market in volume yet; the C219 is old enough that many owners simply move on.
The OM651 engine accounts for the majority of CLS diesel enquiries — and the "Black Death" injector seal failure is the #1 reason CLS owners contact us. This is a manageable, preventable issue with regular servicing, not a reason to avoid the engine entirely.
The CLS is the only Mercedes saloon where petrol enquiries (M276 V6, M157 V8) are a meaningful minority — buyers of the C257 with M256 or M177 are a different cohort from the diesel-focused earlier generation owners.
Editorial Pull-Quote
“If you buy one CLS based on this page, make it a 2014–2016 C218 facelift with the OM654 diesel. It has the style that defines the CLS name, the modern engine with the cleanest reliability record, and values that have already absorbed the steepest depreciation — leaving you with a design icon that won't bankrupt you. MERCEDES CLS — SECTIONS 8-14”
Real UK pricing for every CLS engine — used, reconditioned, and rebuilt supply-only — with independent labour estimates and the honest economics of when to repair vs when to walk away.
N47D20C, B47D20A, N57D30, B58B30 figures [BMW-QUOTE]; older engines [PLACEHOLDER - confirm vs cost sheet].
Fitting a Mercedes CLS engine typically takes 8–22 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer) [MB-QUOTE]. The CLS rule: generation is destiny A C219 CLS (2004–2011) worth £3,000–£9,000 faces a £3,200–£5,500 reconditioned engine cost — that's 40–70% of the car's value before you even pay for labour. A C257 CLS (2018–present) worth £18,000–£45,000 faces the same £3,000–£5,000 reconditioned cost for an OM654 — comfortably within the Mercedes 70% threshold. The same engine family can be a "repair it" on a modern CLS and a "scrap it" on an early C219. Our advice: if the lowest viable reconditioned cost exceeds 70% of what your CLS is actually worth on today's market, get a scrap valuation alongside any repair quote. For a pre-2014 C218 with OM651 showing early injector-seal symptoms, the answer is often "fix it now before it becomes a full engine job." For a C219 with a seized OM629 V8, the honest answer is frequently "walk away." We tell you when to fix it, when to fit a used engine, and when to walk away — because not every CLS is worth saving.
Value the car first; the engine decision follows.
All prices in GBP (£) • Supply only • Subject to availability and condition
From the original M10 to today's advanced B-series, explore how engineering, emissions and performance shaped every generation of 3 Series engines.
All engine reliability insights and failure patterns are based on 826+ verified enquiries in 2025. Data covers the UK market. [BMW-VERIFIED]
Different buyers, different priorities. Here is our verdict on who the Mercedes CLS is perfect for - and who should think twice.
Real talk. The right Mercedes CLS for you depends on your budget, your mileage, and your patience for maintenance. Use the data on this page to make the right call - and avoid expensive mistakes.
Sub-headline: The CLS's design-led appeal means you might be tempted to save a car that isn't financially worth saving.
Our calculator helps you make the honest call.
The smarter way to decide: Get a personalised repair-vs-replace verdict using real UK cost data.
Launch the BMW diagnostic calculator with CLS pre-selected.
We'll identify it first.
Identification is the first step inside the tool.
We'll pinpoint your exact engine code before running the diagnostics.
Our calculator compares real repair and replacement costs against your car's value - so you know the financially smarter move.
Built on Real Data - Every reliability rating and cost range in this guide comes from 306+ real UK CLS enquiries in 2025, plus 4,200+ Mercedes-wide enquiries [MB-VERIFIED] — not manufacturer marketing, not forum guesswork.
We Tell You When Not to Repair - If a £3,200–£5,500 reconditioned engine exceeds 70% of your CLS's actual market value, we tell you to get a scrap valuation. That's the difference between a knowledge base and a sales page.
Vetted Mercedes - Benz Specialists — Our network includes 25+ vetted Mercedes-Benz specialists who work on CLS engines daily — from OM651 injector-seal assessment to M156 timing-chain diagnosis. We don't send CLS owners to generalists.
Part of Engine Finders - mercedesengine.uk is part of the Engine Finders family, the UK's leading engine replacement marketplace — giving you the research depth of an independent authority with a vetted route to action when you need one.
Read our in-depth BMW 3 Series vs 5 Series reliability guide.
Everything you need to choose with confidence.
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