BMW B47 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 BMW B47: 46/100 (moderate risk) versus 73/100 (high risk). The BMW B47 has 3 documented serious faults, the main one being «EGR cooler leaks with risk of engine fire»; the 2.2 CDI (OM646) has 1 documented serious fault, the main one being «Injector seal leak with carbonisation around the seat».

Risk index

BMW B47

High risk · 3 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 202611 sources How we work

Is the BMW B47 reliable?

The BMW B47 (since 2014, successor to the N47) improves the timing chain tensioner, guides and oil supply and greatly reduces the failure rate of its predecessor, but it is not free of problems: the EGR cooler has been the subject of several BMW technical campaigns for engine fire risk since 2018, and the turbo and particulate filter need careful maintenance.^[1][2][3][4]

See the 4 of the BMW B47 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 BMW B47 and 2.2 CDI (OM646)
Item	BMW B47	2.2 CDI (OM646)
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	1,995 cm³	2,148 cm³
Timing	Chain	Chain
Power	114–228 hp	82–170 hp
Production	since 2014^[1]	1998–2010^[5][9][10]
Reliability
Risk index (what is it?)	73High risk	46Moderate risk
Documented faults	4	6
Of high or critical severity	3	1
Worst severity	Critical severity	High severity
Main faults	Critical severity: EGR cooler leaks with risk of engine fire High severity: Timing chain wear (improved, but is it really at the front?) High severity: Premature turbo wear from neglected maintenance	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 €2,000Premature turbo wear from neglected maintenancePublished figure^[3]	up to €300Faulty air flow meter on the 220 CDI (OM 611 and OM 646)Published figure^[11]
Which versions to buy
BuyRecommended versions	None	None
With cautionVersions to be cautious about	B47 114-150 hp, single turbo (2014-)^[2][4] B47 168-190 hp, single turbo (2014-)^[2][4] B47 202-228 hp, twin-turbo (2015-)^[2][4] B47C20 (MINI Cooper D/SD and Countryman, 2014-)^[1][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

BMW B47

See the 19 models with the BMW B47

2.2 CDI (OM646)

Other comparisons

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Sources

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

BMW B47Wikipedia (inglés) · Other source · consulted 26 September 2026
324.000 diésel de BMW tendrán que pasar por el taller en Europa, por un posible riesgo de incendio en la EGRDiariomotor · Motoring press · published 8 August 2018 · consulted 26 September 2026 · in Spanish
Motor BMW B47: problemas, modelos y qué revisarCarexam · Motoring press · consulted 26 September 2026 · in Spanish
Motor BMW B47 - Reparación EspecializadaDasercars · Technical documentation · consulted 26 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
Mercedes-Benz OM646 engineWikipedia · Other source · consulted 27 September 2026
Mercedes-Benz OM611 engineWikipedia · Other source · consulted 27 September 2026
Caudalímetro o sensor MAF: qué es, cómo funciona y cuáles son las averías más frecuentesDiariomotor · Motoring press · consulted 30 October 2026 · in Spanish