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e-Skyactiv D 3.3 vs OM642: which engine is more reliable?

According to our risk index, the e-Skyactiv D 3.3 carries less risk than the OM642: 21/100 (low risk) versus 72/100 (high risk). The e-Skyactiv D 3.3 has 2 documented serious faults, the main one being «Stalling and restart failures due to control unit software»; the OM642 has 4 documented serious faults, the main one being «Broken swirl flaps in the intake manifold».

Risk index

e-Skyactiv D 3.3

21

Low risk · 2 serious faults

Lower risk

Risk index

OM642

72

High risk · 4 serious faults

The index (0–100) weights the severity and frequency of the three most serious documented faults. How it is calculated

13 sourcesHow we work

Is the e-Skyactiv D 3.3 reliable?

The e-Skyactiv D 3.3 is an inline-six diesel with mild-hybrid assistance that Mazda debuted in the CX-60. It is a very recent engine: there is no in-service reliability data, and what is documented are software recalls (stalling, restarting, clutch) fixed at the official dealer.[1][2][3]

See the 2 of the e-Skyactiv D 3.3 faults

Is the OM642 reliable?

The OM642 is Mercedes-Benz's 3.0-litre V6 diesel (2005-2021, 184 to 265 hp), fitted across much of its range and also in the Jeep Grand Cherokee and the Chrysler 300C. It is a robust bottom end with known weak points: the oil cooler seals between the cylinder heads tend to fail between 120,000 and 180,000 km, and the intake swirl flaps can break and damage the engine if they are not checked.[4][5][6]

See the 5 of the OM642 faults

Side-by-side comparison

Comparison of e-Skyactiv D 3.3 and OM642
e-Skyactiv D 3.3OM642
Technical data
TypeEngineEngine
FuelDieselDiesel
Displacement3,283 cm³2,987 cm³
Timing—Chain
Power254 hp184–265 hp
Productionsince 2022[7][8]2005–2021[6][9][10]
Reliability
Risk index (what is it?)21Low risk72High risk
Documented faults25
Of high or critical severity24
Worst severityHigh severityCritical severity
Main faults
  1. High severity: Stalling and restart failures due to control unit software
  2. High severity: Clutch between engine and electric motor that does not re-engage after braking
  1. Critical severity: Broken swirl flaps in the intake manifold
  2. High severity: Oil cooler seal leak (between the cylinder heads)
  3. High severity: Wear and failure of the Bosch piezo injectors
Most expensive documented repairNo reliable dataup to €6,500Wear and failure of the Bosch piezo injectorsPublished figure[5][11]
Which versions to buy
BuyRecommended versionsNoneNone
With cautionVersions to be cautious about
  • 3.3 e-Skyactiv D 254 (T3-VPTS, 2022-present)[1][2][3]
  • OM642 Euro 4, first generation (280/300/320 CDI, 2005-2009)[4][5]
  • OM642 Euro 5, second generation (300/350 CDI and BlueTEC, 2009-2014)[5]
  • OM642 Euro 6 BlueTEC (350 BlueTEC/d, 2014-2021)[5][12][13]
AvoidVersions to avoidNoneNone

Severity of each fault: green, low; amber, medium; red, high; dark red, critical. How we rate them

Cars that each one is fitted to

e-Skyactiv D 3.3

OM642

See the 16 models with the OM642

Other comparisons

With the e-Skyactiv D 3.3

With the OM642

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.

  1. DVSA – base de llamadas a revisión (Mazda CX-60)DVSA (Reino Unido) · Official body · consulted 29 October 2026
  2. Mazda CX-60 (2022 – 2024): engine stall (Safety Gate SR/01913/25)Car-Recalls.eu · Official body · published 23 May 2025 · consulted 29 October 2026
  3. Mazda CX-60: The engine not responding to the accelerator after stopping (KBA 14131R)Car-Recalls.eu · Official body · published 11 August 2025 · consulted 29 October 2026
  4. Mercedes OM642: Zuverlässiger Dauerläufer oder Kostenfalle?Gebrauchtwagenberater · Motoring press · consulted 26 September 2026 · in German
  5. Mercedes OM642 : fiabilité, pannes fréquentes et coûts d'entretienAutoCopilot · Motoring press · published 2026 · consulted 26 September 2026 · in French
  6. Motor diésel Mercedes V6 OM642Motordinámico · Motoring press · published December 2024 · consulted 26 September 2026 · in Spanish
  7. Skyactiv (apartado Skyactiv-D 3.3)Wikipedia (inglés) · Other source · consulted 29 October 2026
  8. Mazda CX-60 3.3 e-Skyactiv D MHEV 254ps AWD HomuraPractical Caravan · Motoring press · consulted 29 October 2026
  9. Mercedes-Benz OM642 engineWikipedia · Other source · consulted 26 September 2026
  10. Mercedes-Benz OM 642Wikipedia (alemán) · Other source · consulted 26 September 2026 · in German
  11. Sprinter Injector Problems (OM651, OM642 & CDI)Sprinterpedia · Motoring press · consulted 26 September 2026
  12. Abgas-Skandal: KBA findet angeblich deutliche Hinweise auf illegale Abschalteinrichtungen in Mercedes-Dieselautosheise online · General press · published 14 July 2017 · consulted 26 September 2026 · in German
  13. Daimler muss 774.000 Fahrzeuge zurückrufenKleine Zeitung · General press · published 11 June 2018 · consulted 26 September 2026 · in German