OM642 vs 2.0 dCi: which engine is more reliable?

According to our risk index, the 2.0 dCi carries less risk than the OM642: 52/100 versus 72/100 (both high risk). The OM642 has 4 documented serious faults, the main one being «Broken swirl flaps in the intake manifold»; the 2.0 dCi has 2 documented serious faults, the main one being «Premature turbocharger failure».

Risk index

OM642

High risk · 4 serious faults

Risk index

2.0 dCi

High risk · 2 serious faults

Lower risk

The index (0–100) weights the severity and frequency of the three most serious documented faults. How it is calculated

Reviewed on 27 September 202618 sources How we work

Is the OM642 reliable?

The OM642 is Mercedes-Benz's 3.0-litre V6 diesel (2005-2021, 184 to 265 hp), fitted across much of its range and also in the Jeep Grand Cherokee and the Chrysler 300C. It is a robust bottom end with known weak points: the oil cooler seals between the cylinder heads tend to fail between 120,000 and 180,000 km, and the intake swirl flaps can break and damage the engine if they are not checked.^[1][2][3]

See the 5 of the OM642 faults

Is the 2.0 dCi reliable?

The 2.0 dCi (M9R) is a Renault-Nissan Alliance diesel with known, well-documented weak points: the turbo and the EGR valve fail relatively often, the particulate filter clogs up in urban use, and there are cases of injectors and even the timing chain failing earlier than expected in several of the models that use it.^[4][5][6][7]

See the 5 of the 2.0 dCi faults

Side-by-side comparison

Comparison of OM642 and 2.0 dCi
Item	OM642	2.0 dCi
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	2,987 cm³	1,995 cm³
Timing	Chain	Chain
Power	184–265 hp	90–177 hp
Production	2005–2021^[3][8][9]	2005–2016^{[10][11][12][13]}
Reliability
Risk index (what is it?)	72High risk	52High risk
Documented faults	5	5
Of high or critical severity	4	2
Worst severity	Critical severity	Critical severity
Main faults	Critical severity: Broken swirl flaps in the intake manifold High severity: Oil cooler seal leak (between the cylinder heads) High severity: Wear and failure of the Bosch piezo injectors	High severity: Premature turbocharger failure Critical severity: Timing chain wear or breakage Medium severity: Clogged particulate filter (DPF)
Most expensive documented repair	up to €6,500Wear and failure of the Bosch piezo injectorsPublished figure^[2][14]	No reliable data
Which versions to buy
BuyRecommended versions	None	None
With cautionVersions to be cautious about	OM642 Euro 4, first generation (280/300/320 CDI, 2005-2009)^[1][2] OM642 Euro 5, second generation (300/350 CDI and BlueTEC, 2009-2014)^[2] OM642 Euro 6 BlueTEC (350 BlueTEC/d, 2014-2021)^[2][15][16]	2.0 dCi 130-150 (M9R, cars, 2005-2012)^[4][5][7] 2.0 dCi 160-177 (M9R, higher-output cars, 2006-2016)^[5][6][17] 2.0 dCi 90-115 (M9R, vans, 2006-2014)^[18]
AvoidVersions to avoid	None	None

Severity of each fault: green, low; amber, medium; red, high; dark red, critical. How we rate them

Cars that each one is fitted to

OM642

See the 16 models with the OM642

2.0 dCi

See the 12 models with the 2.0 dCi

Other comparisons

With the OM642

With the 2.0 dCi

Compare other engines

First engine

Second engine

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Sources

Every fact on this page links to its source. If you find an error, let us know.

Mercedes OM642: Zuverlässiger Dauerläufer oder Kostenfalle?Gebrauchtwagenberater · Motoring press · consulted 26 September 2026 · in German
Mercedes OM642 : fiabilité, pannes fréquentes et coûts d'entretienAutoCopilot · Motoring press · published 2026 · consulted 26 September 2026 · in French
Motor diésel Mercedes V6 OM642Motordinámico · Motoring press · published December 2024 · consulted 26 September 2026 · in Spanish
Fiabilité Renault Laguna 3 : pannes et avisFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité Renault Koleos : pannes et avisFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité Renault Espace 4 : pannes et avisFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité Nissan Qashqai : pannes et avisFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Mercedes-Benz OM642 engineWikipedia · Other source · consulted 26 September 2026
Mercedes-Benz OM 642Wikipedia (alemán) · Other source · consulted 26 September 2026 · in German
Anexo:Motores de RenaultWikipedia · Other source · consulted 27 September 2026 · in Spanish
Renault KoleosWikipedia · Other source · consulted 27 September 2026
Renault Mégane IIIWikipedia · Other source · consulted 27 September 2026 · in French
Renault Grand Espace 2.0 dCi PrivilegeAutopista · Motoring press · published 19 September 2006 · consulted 27 September 2026 · in Spanish
Sprinter Injector Problems (OM651, OM642 & CDI)Sprinterpedia · Motoring press · consulted 26 September 2026
Abgas-Skandal: KBA findet angeblich deutliche Hinweise auf illegale Abschalteinrichtungen in Mercedes-Dieselautosheise online · General press · published 14 July 2017 · consulted 26 September 2026 · in German
Daimler muss 774.000 Fahrzeuge zurückrufenKleine Zeitung · General press · published 11 June 2018 · consulted 26 September 2026 · in German
Fiabilité Nissan X-Trail : pannes et avisFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Renault TraficWikipedia · Other source · consulted 27 September 2026