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OM 640OM640OM 640 DE 20 LAOM 640.940OM 640.941

2.0 CDI (OM640) engine: faults and reliability

Mercedes-Benz OM640 (2.0 CDI de 4 cilindros) · Mercedes-Benz

The OM640 is the 2.0 CDI four-cylinder diesel that Mercedes-Benz fitted between 2004 and 2012 to the A-Class (W169) and B-Class (W245), with outputs from 82 to 140 hp (160/180/200 CDI). Its mechanical base is considered reliable, with the EGR valve and the injectors being typical weak points of diesels of that era; the problem owners cite most, however, is the Autotronic (CVT) automatic gearbox, optional on the 180 CDI and 200 CDI.[1][2][3][4]

Risk index
36
Moderate risk · what it is
Documented faults
4
2 of high or critical severity
Timing
Chain
Technical data[1][5][6][7]
Production
2004–2012
2 models on this site

11 sourcesHow we work

Which 2.0 CDI (OM640) versions should you buy?

Our verdict for each version, based on the documented faults.

  • 160 CDI (60 kW/82 hp, A-Class only)

    2004–2012 · 82 hp · OM 640 DE 20 LA

    With caution

    It shares the mechanical base and the generic weak points of the OM640 (EGR, injectors, turbo), but since it was not offered with the Autotronic gearbox it avoids the most expensive and most cited problem of this model's engine-transmission combination. We have not found owner testimonies specific to this 82 hp version.[2][6]

  • 180 CDI (80 kW/109 hp)

    2004–2012 · 109 hp · OM 640 DE 20 LA, OM 640.940

    With caution

    It is the version with the most owner testimonies analysed by a French source (234), which places EGR valve fouling as the most repeated chronic defect, followed at some distance by the dual-mass flywheel, the overrunning alternator pulley and the injectors. You should also check the gearbox history if the specific car has the Autotronic.[2][3]

  • 200 CDI (103 kW/140 hp)

    2004–2012 · 140 hp · OM 640 DE 20 LA, OM 640.941

    With caution

    A French source analysing 114 owner testimonies describes a "quite convincing" reliability record for this version, but penalised above all by the gearbox: 24 of the 114 testimonies cite a transmission fault, well ahead of the EGR (4), the turbo (3) or the injectors (2). It is the version that benefited most from the Autotronic's extra torque, and also the one that concentrates the most complaints about it.[2][4]

Buy: No known serious faults, or they have already been corrected, in this version. With caution: Worth buying if something specific is verified: history, a replaced part or a completed campaign. Avoid: High risk of a serious fault that is hard to check for or prevent.

Known faults of the 2.0 CDI (OM640)

Sorted from most to least important (severity × frequency).

  1. 1Critical severityFrequency: CommonTransmissionCostly failure of the Autotronic (CVT) automatic gearboxYes: the Autotronic continuously variable gearbox, optional on the 180 CDI and 200 CDI, is the problem cited most by owners of the 140 hp version (24 of 114 testimonies) and a fault hotspot according to the ADAC up to 2006. A German source recommends avoiding it and choosing the manual gearbox.
  2. 2High severityFrequency: OccasionalTurboPremature turbocharger wear or failureIt is one of the typical weak points identified for the OM640, although with fewer cases than the EGR or the Autotronic gearbox. A specialist German source includes it among the parts to watch, and owner testimonies for the 140 hp version document a few failures, without detailing the exact mechanism.
  3. 3Medium severityFrequency: CommonEmissions controlEGR valve clogged with sootYes: the EGR valve is the problem OM640 owners cite most. A specialist German source points to it as the thing to watch before any other, and a French source collecting 234 testimonies for the 109 hp version places it as the most repeated chronic defect, ahead of the injectors.
  4. 4Medium severityFrequency: OccasionalInjectionCarbon build-up in the injectorsYes, although with fewer cases than the EGR: the OM640's injectors can build up soot with use, which a specialist German source describes as a cause of expensive repairs. Owner testimonies place it as a secondary problem compared with the EGR or the Autotronic gearbox.

Severity colours: low, medium, high, critical. How we rate them

By part

Compare each fault with the same part on other engines: symptoms, cost and affected models.

Symptoms of these faults

What the 2.0 CDI (OM640) is

The OM640 is an inline four-cylinder diesel, 1,991 cc (83 x 92 mm), with a 4-valve-per-cylinder head, direct common-rail injection, a turbocharger with intercooler and camshaft drive by two chains. Mechanically, the three power levels (160, 180 and 200 CDI) are identical to one another; the differences in power and torque are achieved only by varying the injection electronics and the turbocharging. It is a transversely mounted engine, tilted about 60° forwards and positioned behind the front axle, the characteristic layout of the "sandwich floor" of the first A-Class and B-Class.[1][5]

It reached the market with the launch of the second A-Class (W169) in June 2004, built in Rastatt (Germany) and Samut Prakan (Thailand) as a 3- and 5-door body, and remained until the end of that generation in 2012, with a facelift in spring 2008. A year after the W169 came the first B-Class (W245, June 2005-2011), also built in Rastatt, with its own facelift in 2008-2009 that added the start-stop system and the BlueEFFICIENCY package. The B-Class never offered the entry-level 160 CDI: it used the OM640 only as the 180 CDI and 200 CDI.[6][7][8][9][10][11]

The 160 CDI (60 kW/82 hp, 180 Nm) was sold only with a 5-speed manual gearbox. The 180 CDI (80 kW/109 hp, 250 Nm) and the 200 CDI (103 kW/140 hp, 300 Nm) added a sixth manual gear and, as an option, the Autotronic continuously variable transmission (CVT); this same Autotronic was also offered with the A 200 Turbo petrol engine, but not with the 160 CDI.[6]

A specialist German used-car source describes the OM640 as "relativ unauffällig" (relatively unremarkable/trouble-free), pointing to the EGR valve as the problem to watch before any other. A French source that compiles owner testimonies sums up the reliability record of the 200 CDI (140 hp) as "quite convincing despite problems on the transmission side", and places EGR fouling as the most cited chronic defect on the 109 hp version (180 CDI), with the injectors as a secondary problem on both.[2][3][4]

The same German source includes the particulate filter (DPF), the dual-mass flywheel and the turbocharger among the typical weak points of this engine, in the same generic list in which it mentions the EGR and the injectors. However, the only source with quantified data from real testimonies that we have found (114 cases analysed for the 140 hp version) records no particulate filter fault, compared with 24 gearbox cases, 4 EGR, 3 turbo and 2 injector cases. That is why we do not include the particulate filter as a separate fault: the generic claim is not supported by data specific to this engine.[2][4]

Manufacturer
Mercedes-Benz (Daimler)
Family
Familia OM640 de diésel de 4 cilindros con common rail de Mercedes-Benz, montada en exclusiva sobre la primera plataforma "sandwich" de la Clase A y la Clase B (comparte arquitectura básica con el OM639 de 3 cilindros del Smart Forfour y el Mitsubishi Colt, no cubierto en esta ficha)
Fuel
Diesel
Displacement
1,991 cm³
Cylinders
4
Fuel system
Turbo
Injection
Common rail
Timing
Chain
Power
82–140 hp
Peak torque
300 Nm
Production
2004–2012
Makes
Mercedes-Benz

Technical data[1][5][6][7]

What changed between versions

  1. 2004–2012

    160 CDI (60 kW/82 hp, A-Class only)

    Entry-level version of the OM640, with 180 Nm of torque, fitted only to the A-Class (W169); the B-Class never offered it. It was sold exclusively with a 5-speed manual gearbox, with no Autotronic automatic gearbox option.[6][7]

  2. 2004–2012

    180 CDI (80 kW/109 hp)

    Mid-level power version (250 Nm), available in the A-Class from 2004 and in the B-Class from its launch in 2005, with a 6-speed manual gearbox as standard and the Autotronic (CVT) as an option.[6][7]

  3. 2004–2012

    200 CDI (103 kW/140 hp)

    Highest-output version of the OM640 (300 Nm), available in the A-Class from 2004 and in the B-Class from 2005, with a 6-speed manual gearbox as standard and the Autotronic (CVT) as an option.[6][7]

Cars fitted with the 2.0 CDI (OM640)

2 models sold in Europe. Open each one to see all their faults and the buying checklist.

Mercedes-Benz

Compare the 2.0 CDI (OM640)

Maintenance parts for the 2.0 CDI (OM640)

The parts replaced at services and when the timing belt or chain is changed, searched for this engine. Confirm the part number with the registration plate or VIN.

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Sources

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

  1. Mercedes-Benz OM 640Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  2. Mercedes A-Klasse (W169) – Typische Probleme & SchwachstellenGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  3. Fiabilité des 180d / 180 CDI MercedesFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  4. Fiabilité 200 CDI MercedesFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  5. Mercedes-Benz OM640 engineWikipedia · Other source · consulted 27 September 2026
  6. Mercedes-Benz W169Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  7. Mercedes-Benz W245Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  8. Mercedes-Benz W169Wikipedia · Other source · consulted 27 September 2026
  9. Mercedes-Benz W245Wikipedia · Other source · consulted 27 September 2026
  10. Mercedes-Benz Clase AWikipedia · Other source · consulted 27 September 2026 · in Spanish
  11. Mercedes-Benz Clase BWikipedia · Other source · consulted 27 September 2026 · in Spanish