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

According to our risk index, the 2.2 CDI (OM646) carries less risk than the 2.0 HDi: 46/100 (moderate risk) versus 55/100 (high risk). The 2.0 HDi has 2 documented serious faults, the main one being «Variable-geometry turbo failures (actuator, sensors and clogging)»; the 2.2 CDI (OM646) has 1 documented serious fault, the main one being «Injector seal leak with carbonisation around the seat».

Risk index

2.0 HDi

High risk · 2 serious faults

Risk index

2.2 CDI (OM646)

Moderate risk · 1 serious fault

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 202616 sources How we work

Is the 2.0 HDi reliable?

It is a robust diesel in its simplest 90 hp version, but the 136 to 140 hp generation with a DPF (2004-2011) concentrates the engine's problems: turbo, DPF, EGR and, above all, a dual-mass flywheel that fails very often. The BlueHDi engines (from 2013) are mechanically more reliable, but add an AdBlue tank that can crystallise; the OCU (Spanish consumer organisation) has reported this fault in Spain and Stellantis covers it with a compensation programme.^[1][2][3][4]

See the 5 of the 2.0 HDi faults

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.^[5][6][7][8]

See the 6 of the 2.2 CDI (OM646) faults

Side-by-side comparison

Comparison of 2.0 HDi and 2.2 CDI (OM646)
Item	2.0 HDi	2.2 CDI (OM646)
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	1,997 cm³	2,148 cm³
Timing	Timing belt (dry)	Chain
Power	90–180 hp	82–170 hp
Production	1999–2021^{[1][9][10][11][12]}	1998–2010^[5][13][14]
Reliability
Risk index (what is it?)	55High risk	46Moderate risk
Documented faults	5	6
Of high or critical severity	2	1
Worst severity	High severity	High severity
Main faults	High severity: Variable-geometry turbo failures (actuator, sensors and clogging) High severity: DPF clogging on additive-type systems (Eolys/cerine) Medium severity: Premature dual-mass flywheel wear (from 107/110 hp)	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
Most expensive documented repair	up to €1,200AdBlue tank crystallisation and failures (BlueHDi)Published figure^[3][4][15]	up to €300Faulty air flow meter on the 220 CDI (OM 611 and OM 646)Published figure^[16]
Which versions to buy
BuyRecommended versions	2.0 HDi 90 (DW10TD, 1999-2005)^[1] 2.0 HDi 150/163 DPF (DW10C / DW10CTED4, 2007-2013)^[1]	None
With cautionVersions to be cautious about	2.0 HDi 107/110 (DW10ATED / DW10ATED4, 2000-2008)^[1] 2.0 HDi 136/138/140 DPF (DW10BTED4, 2004-2011)^[1] 2.0 BlueHDi 120/150/163/180 (DW10FE / DW10FD / DW10FC, 2013-2021)^[1][2][3][4]	OM611 (predecessor, 2.2 CDI, 1998-2006)^[6][8] OM646 pre-EVO (2002-2007, Euro 3/4, 88-150 hp)^[6][7][8] OM646 EVO (2006-2009, up to 170 hp)^[8]
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

2.0 HDi

See the 19 models with the 2.0 HDi

2.2 CDI (OM646)

Other comparisons

With the 2.0 HDi

With the 2.2 CDI (OM646)

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Sources

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

Fiabilité du 2.0 HDIFiches-Auto · Motoring press · consulted 27 September 2026 · in French
AdBlue : problèmes en pagailleFiches-Auto · Motoring press · consulted 27 September 2026 · in French
Más problemas para Stellantis: ahora tendrá que indemnizar también a los afectados por el AdBlueAutopista · Motoring press · published 30 December 2024 · consulted 27 September 2026 · in Spanish
El fallo que afecta a cientos de coches y que ahora la OCU denuncia para reclamar indemnizacionesAutopista · Motoring press · published 29 May 2023 · consulted 27 September 2026 · in Spanish
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
PSA EW/DW engineWikipedia (inglés) · Other source · consulted 27 September 2026
Peugeot 307Wikipedia (español) · Other source · consulted 27 September 2026 · in Spanish
Peugeot 3008Wikipedia (español) · Other source · consulted 27 September 2026 · in Spanish
Citroën C4 PicassoWikipedia (español) · Other source · consulted 27 September 2026 · in Spanish
Mercedes-Benz OM646 engineWikipedia · Other source · consulted 27 September 2026
Mercedes-Benz OM611 engineWikipedia · Other source · consulted 27 September 2026
Aditivo AdBlue: qué debes usar para evitar una reparación de 2.000 euros en tu coche diéselAutopista · Motoring press · published 1 April 2026 · 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