BMW N47 vs OM656: which engine is more reliable?

According to our risk index, the OM656 carries less risk than the BMW N47: 39/100 (moderate risk) versus 87/100 (very high risk). The BMW N47 has 3 documented serious faults, the main one being «Rear timing chain stretch and breakage»; the OM656 has 2 documented serious faults, the main one being «Leak in the vacuum-driven coolant pump (fire risk)».

Risk index

BMW N47

Very high risk · 3 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 202621 sources How we work

Is the BMW N47 reliable?

The BMW N47 (2007-2016, including its MINI derivatives N47C16/N47C20) is mechanically sound in the basics, but it carries a serious, well-documented design flaw: the rear timing chain wears or breaks prematurely on many units, especially those built between 2007 and 2009, with repairs from €1,500 to over €8,000 if the engine ends up damaged. Without a clear timing history, great caution is needed.^[1][2][3][4]

See the 5 of the BMW N47 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 BMW N47 and OM656
Item	BMW N47	OM656
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	1,995 cm³	2,925 cm³
Timing	Chain	Chain
Power	90–218 hp	272–367 hp
Production	2007–2016^{[1][13][14][15]}	since 2017^[5][6][16]
Reliability
Risk index (what is it?)	87Very high risk	39Moderate risk
Documented faults	5	4
Of high or critical severity	3	2
Worst severity	Critical severity	Critical severity
Main faults	Critical severity: Rear timing chain stretch and breakage Critical severity: Broken intake manifold swirl flaps High severity: Turbo and wastegate valve failure	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 €3,000Rear timing chain stretch and breakagePublished figure^{[17][18][19][20][21]}	No reliable data
Which versions to buy
BuyRecommended versions	None	OM656 3.0 diesel with electric assistance (D 30, from 2023)^[8][9][11]
With cautionVersions to be cautious about	N47D20 116 hp (K0/K1, 2007-2014)^[1][4] N47D20 143 hp (U0/U1, 2007-2014)^[1][4] N47D20 177-184 hp (O0/O1, 2007-2014)^[1][4] N47D20 204-218 hp twin-turbo (2007-2014)^[1][4] N47C16 90-112 hp (MINI Cooper D, 2010-2016)^[14] N47C20 112-143 hp (MINI Cooper SD, 2011-2016)^[15]	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

BMW N47

See the 12 models with the BMW N47

OM656

See the 11 models with the OM656

Other comparisons

With the BMW N47

With the OM656

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Sources

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

BMW N47Wikipedia (inglés) · Other source · consulted 26 September 2026
BMW's timing chain problem comes back to haunt carmakerThe Irish Times · General press · consulted 26 September 2026
El problema de la cadena de distribución en los motores N47 de BMWSeis en Línea · Motoring press · consulted 26 September 2026 · in Spanish
Fallo en la cadena de distribución BMW motores N47Arroyo Auto, Especialista BMW MINI · Technical documentation · consulted 26 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
BMW N47D20 engine specifications, problems and reliabilityBimmerPulse · Technical documentation · consulted 26 September 2026
N47C16A MotorMotorinsel · Technical documentation · consulted 26 September 2026
N47C20A MotorMotorinsel · Technical documentation · consulted 26 September 2026
Mercedes-Benz S-Class (W222)Wikipedia · Other source · consulted 9 October 2026
Motor N47 - precio cambio cadena BMWTaller Barcelona (Dasercars) · Technical documentation · consulted 26 September 2026 · in Spanish
Precio sustitución cadenas motor N47 BMW MINIArroyo Auto, Especialista BMW MINI · Technical documentation · consulted 26 September 2026 · in Spanish
Motor BMW N47 - Reparación EspecializadaDasercars · Technical documentation · consulted 26 September 2026 · in Spanish
Rotura cadena distribución y rotura motor N47OCU · Consumer association · published 2 September 2021 · consulted 26 September 2026 · in Spanish
Problema cadena BMW motor N47, qué hacer y solucionesRecomotor Blog · Motoring press · consulted 26 September 2026 · in Spanish