2.0 HDi vs OM656: which engine is more reliable?

According to our risk index, the OM656 carries less risk than the 2.0 HDi: 39/100 (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 OM656 has 2 documented serious faults, the main one being «Leak in the vacuum-driven coolant pump (fire risk)».

Risk index

2.0 HDi

High risk · 2 serious faults

Risk index

OM656

Moderate 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 9 October 202618 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 OM656 reliable?

The OM656 is the roughly 3.0-litre in-line six-cylinder diesel with which Mercedes-Benz replaced the OM642 V6 from 2017 in the S-Class, E-Class, CLS, GLE, GLS and G-Class (350 d, 400 d and 450 d). It has few documented faults: the known campaign is the coolant pump one of 2021-2022, and the timing chain recall that circulates belongs to the OM654. Guides warn about the AdBlue/SCR system, the EGR and, in isolated cases, the roller rocker arms, without figures.^{[5][6][7][8][9][10][11][12]}

See the 4 of the OM656 faults

Side-by-side comparison

Comparison of 2.0 HDi and OM656
Item	2.0 HDi	OM656
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	1,997 cm³	2,925 cm³
Timing	Timing belt (dry)	Chain
Power	90–180 hp	272–367 hp
Production	1999–2021^{[1][13][14][15][16]}	since 2017^[5][6][17]
Reliability
Risk index (what is it?)	55High risk	39Moderate risk
Documented faults	5	4
Of high or critical severity	2	2
Worst severity	High severity	Critical 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)	Critical severity: Leak in the vacuum-driven coolant pump (fire risk) Medium severity: NOx sensor failure and AdBlue (SCR) system warnings Medium severity: EGR valve clogged with soot after short journeys
Most expensive documented repair	up to €1,200AdBlue tank crystallisation and failures (BlueHDi)Published figure^[3][4][18]	No reliable data
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]	OM656 3.0 diesel with electric assistance (D 30, from 2023)^[8][9][11]
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]	OM656 2.9 diesel 350 d (OM 656 D 29 R SCR, from 2017)^[7][8][9] OM656 2.9 diesel 400 d (OM 656 D 29 SCR, from 2017)^{[7][8][9][11]}
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

OM656

See the 11 models with the OM656

Other comparisons

With the 2.0 HDi

With the OM656

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.

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 OM656 engineWikipedia · Other source · consulted 9 October 2026
Mercedes-Benz OM 656Wikipedia (alemán) · Other source · consulted 9 October 2026 · in German
Rückruf für OM 656 und OM 654 Motoren wegen KühlmittelpumpeMBpassion · Motoring press · published 9 December 2021 · consulted 9 October 2026 · in German
Mercedes-Rückruf: Kühlmittelprobleme bei DieselautosAUTOHAUS · Motoring press · published 5 January 2022 · consulted 9 October 2026 · in German
DVSA – base de llamadas a revisiónDVSA (Reino Unido) · Other source · consulted 9 October 2026
Mercedes-Benz GLC (X253): Alle typischen Probleme & MängelGebrauchtwagenberater · Motoring press · consulted 9 October 2026 · in German
Mercedes OM656 Diesel: Häufige Probleme, Ursachen & Tipps zur Vermeidung von MotorschädenMBpassion · Motoring press · published 19 February 2026 · consulted 9 October 2026 · in German
Mercedes-Benz OM656 Engine Guide: Reliability, Common Problems & Tuning PotentialEuro Premium Parts · Technical documentation · consulted 9 October 2026
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 S-Class (W222)Wikipedia · Other source · consulted 9 October 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