2.2 CDI (OM646) vs 2.0 dCi: which engine is more reliable?

According to our risk index, the 2.2 CDI (OM646) carries less risk than the 2.0 dCi: 46/100 (moderate risk) versus 52/100 (high risk). The 2.2 CDI (OM646) has 1 documented serious fault, the main one being «Injector seal leak with carbonisation around the seat»; the 2.0 dCi has 2 documented serious faults, the main one being «Premature turbocharger failure».

Risk index

2.2 CDI (OM646)

Moderate risk · 1 serious fault

Lower risk

Risk index

2.0 dCi

High risk · 2 serious faults

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

Reviewed on 27 September 202617 sources How we work

Is the 2.2 CDI (OM646) reliable?

The OM646 is the 2.2 CDI four-cylinder diesel that Mercedes-Benz fitted between 2002 and 2010 to the C-Class, E-Class, Vito/Viano and Sprinter, as the successor to the OM611 (1998-2006). It is a fundamentally sound engine, considered robust in its mechanical base, but with known and well-documented faults: leaks at the injector seals, a clogged EGR valve, particulate filter sensor failures and a short-lived water pump on some versions.^[1][2][3][4]

See the 6 of the 2.2 CDI (OM646) 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.^[5][6][7][8]

See the 5 of the 2.0 dCi faults

Side-by-side comparison

Comparison of 2.2 CDI (OM646) and 2.0 dCi
Item	2.2 CDI (OM646)	2.0 dCi
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	2,148 cm³	1,995 cm³
Timing	Chain	Chain
Power	82–170 hp	90–177 hp
Production	1998–2010^[1][9][10]	2005–2016^{[11][12][13][14]}
Reliability
Risk index (what is it?)	46Moderate risk	52High risk
Documented faults	6	5
Of high or critical severity	1	2
Worst severity	High severity	Critical severity
Main faults	High severity: Injector seal leak with carbonisation around the seat Medium severity: EGR valve clogged or seized by soot Medium severity: Leak and premature failure of the water pump	High severity: Premature turbocharger failure Critical severity: Timing chain wear or breakage Medium severity: Clogged particulate filter (DPF)
Most expensive documented repair	up to €300Faulty air flow meter on the 220 CDI (OM 611 and OM 646)Published figure^[15]	No reliable data
Which versions to buy
BuyRecommended versions	None	None
With cautionVersions to be cautious about	OM611 (predecessor, 2.2 CDI, 1998-2006)^[2][4] OM646 pre-EVO (2002-2007, Euro 3/4, 88-150 hp)^[2][3][4] OM646 EVO (2006-2009, up to 170 hp)^[4]	2.0 dCi 130-150 (M9R, cars, 2005-2012)^[5][6][8] 2.0 dCi 160-177 (M9R, higher-output cars, 2006-2016)^[6][7][16] 2.0 dCi 90-115 (M9R, vans, 2006-2014)^[17]
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

2.2 CDI (OM646)

2.0 dCi

See the 12 models with the 2.0 dCi

Other comparisons

With the 2.2 CDI (OM646)

With the 2.0 dCi

Compare other engines

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Sources

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

Mercedes-Benz OM 646/OM 647/OM 648Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
Mercedes C-Klasse W203 – Typische Probleme & SchwachstellenGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
Fiabilité 200 CDI MercedesFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité 220 CDIFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
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 OM646 engineWikipedia · Other source · consulted 27 September 2026
Mercedes-Benz OM611 engineWikipedia · Other source · consulted 27 September 2026
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
Caudalímetro o sensor MAF: qué es, cómo funciona y cuáles son las averías más frecuentesDiariomotor · Motoring press · consulted 30 October 2026 · in Spanish
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