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OM654 vs 2.3 dCi (M9T): which engine is more reliable?

According to our risk index, the 2.3 dCi (M9T) carries less risk than the OM654: 32/100 (moderate risk) versus 63/100 (high risk). The OM654 has 3 documented serious faults, the main one being «Timing chain wear or breakage (2016 to 2021 units)»; the 2.3 dCi (M9T) has 2 documented serious faults, the main one being «Clogged or broken EGR valve damaging the turbo».

Risk index

OM654

63

High risk · 3 serious faults

Risk index

2.3 dCi (M9T)

32

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

10 sourcesHow we work

Is the OM654 reliable?

The OM654 is the 2.0-litre four-cylinder diesel with which Mercedes-Benz replaced the OM651 from 2016, fitted to most of its passenger cars and mid-size vans. It has a reputation for reliability: we found no mechanical faults as serious and widespread as on the brand's earlier diesels, although there were recalls for the timing chain (units from 2016 to 2021) and the coolant pump, and the NOx sensor or AdBlue system fail with some frequency.[1][2][3][4]

See the 4 of the OM654 faults

Is the 2.3 dCi (M9T) reliable?

The 2.3 dCi M9T is a van diesel with good durability if maintenance is kept up. The weak points cited are the EGR and the turbo, the injectors, and the particulate filter in urban use; the sources are mostly opinion websites.[5][6]

See the 5 of the 2.3 dCi (M9T) faults

Side-by-side comparison

Comparison of OM654 and 2.3 dCi (M9T)
OM6542.3 dCi (M9T)
Technical data
TypeEngineEngine
FuelDieselDiesel
Displacement1,950 cm³2,300 cm³
TimingChainChain
Power116–272 hp100–180 hp
Productionsince 2016[1][2]since 2010[5][6][7]
Reliability
Risk index (what is it?)63High risk32Moderate risk
Documented faults45
Of high or critical severity32
Worst severityCritical severityHigh severity
Main faults
  1. Critical severity: Timing chain wear or breakage (2016 to 2021 units)
  2. Critical severity: Leak in the vacuum-operated coolant pump (overheating risk)
  3. High severity: Wear of the turbocharger and charge-air intercooler
  1. High severity: Clogged or broken EGR valve damaging the turbo
  2. Medium severity: Faulty injectors on the 2.3 dCi
  3. Medium severity: Diesel particulate filter (DPF) clogged in urban use
Most expensive documented repairup to €850NOx sensor failure and SCR/AdBlue system warningsPublished figure[4][8]up to €2,300Clogged or broken EGR valve damaging the turboPublished figure[5][9]
Which versions to buy
BuyRecommended versionsNone
  • 2.3 dCi 100-125 hp (M9T)[6]
  • 2.3 dCi 130-145 hp (M9T)[6]
With cautionVersions to be cautious about
  • OM654 first generation (2016-2021)[3][4]
  • OM654 M, with 48 V mild hybrid (since 2021)[3][4][8]
  • 2.3 dCi 150-180 hp (M9T, some twin-turbo)[6]
  • 2.3 dCi in the Navara D23 (NP300)[10]
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

OM654

See the 9 models with the OM654

2.3 dCi (M9T)

Other comparisons

With the OM654

With the 2.3 dCi (M9T)

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. Mercedes-Benz OM654 engineWikipedia · Other source · consulted 27 September 2026
  2. Mercedes-Benz OM 654Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
  3. Mercedes-Benz GLC (X253): Alle typischen Probleme & MängelGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  4. Fiabilité Mercedes Classe E (2016-2023)Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  5. Renault Master III 2.3 dCi 130: fiabilité, pannes et coûtsCarverif · Other source · consulted 5 October 2026 · in French
  6. Fiabilité Renault Master 2.3 dCiCarverif · Other source · consulted 5 October 2026 · in French
  7. Renault Master (tercera generación)Wikipedia · Other source · consulted 5 October 2026
  8. Fiabilité Mercedes GLC (2015-2022)Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  9. Fiabilité du Renault Master RT 2.3 dCi: analyse complèteCarverif · Other source · consulted 5 October 2026 · in French
  10. Nissan Navara wymaga zmian systemu oczyszczania spalinAutokatalog.pl · Motoring press · published 23 August 2023 · consulted 5 October 2026 · in another language