OM654 vs D4/D5: which engine is more reliable?

According to our risk index, the OM654 carries less risk than the D4/D5: 63/100 versus 64/100 (both high risk). The OM654 has 3 documented serious faults, the main one being «Timing chain wear or breakage (2016 to 2021 units)»; the D4/D5 has 2 documented serious faults, the main one being «Auxiliary belt breakage that takes the timing belt with it (5-cylinder)».

Risk index

OM654

High risk · 3 serious faults

Lower risk

Risk index

D4/D5

High risk · 2 serious faults

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

Reviewed on 27 September 202612 sources How 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 D4/D5 reliable?

The Volvo D5/D4 covers two different engines: the classic 5-cylinder (2001-2016, D5244T/D5204) and the 4-cylinder VEA (D4204T, from 2013). On the former, several owners document the auxiliary belt breaking and taking the timing belt with it, destroying the engine; on the VEA the most common problems are the EGR, the DPF and oil consumption that can damage the turbo from 90,000-150,000 km. Neither is an engine to buy without checking its service history.^[5][6][7][8]

See the 6 of the D4/D5 faults

Side-by-side comparison

Comparison of OM654 and D4/D5
Item	OM654	D4/D5
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	1,950 cm³	—
Timing	Chain	Timing belt (dry)
Power	116–272 hp	120–235 hp
Production	since 2016^[1][2]	2001–2024^[5][6][9]
Reliability
Risk index (what is it?)	63High risk	64High risk
Documented faults	4	6
Of high or critical severity	3	2
Worst severity	Critical severity	Critical severity
Main faults	Critical severity: Timing chain wear or breakage (2016 to 2021 units) Critical severity: Leak in the vacuum-operated coolant pump (overheating risk) High severity: Wear of the turbocharger and charge-air intercooler	Critical severity: Auxiliary belt breakage that takes the timing belt with it (5-cylinder) High severity: High oil consumption from 90,000-150,000 km that harms the turbo (VEA) Medium severity: Clogged EGR valve or EGR cooler leaking into the intake
Most expensive documented repair	up to €850NOx sensor failure and SCR/AdBlue system warningsPublished figure^[4][10]	No reliable data
Which versions to buy
BuyRecommended versions	None	None
With cautionVersions to be cautious about	OM654 first generation (2016-2021)^[3][4] OM654 M, with 48 V mild hybrid (since 2021)^[3][4][10]	2.4/2.0 D3/D4/D5 5-cylinder (D5244T/D5204, 2001-2016)^[7][11] 2.0 D2/D3/D4/D5 VEA 4-cylinder (D4204T, 2013-2024)^[7][8][12]
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

OM654

See the 9 models with the OM654

D4/D5

See the 14 models with the D4/D5

Other comparisons

With the OM654

With the D4/D5

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Sources

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

Mercedes-Benz OM654 engineWikipedia · Other source · consulted 27 September 2026
Mercedes-Benz OM 654Wikipedia (alemán) · Other source · consulted 27 September 2026 · in German
Mercedes-Benz GLC (X253): Alle typischen Probleme & MängelGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
Fiabilité Mercedes Classe E (2016-2023)Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Volvo Engine ArchitectureWikipedia · Other source · consulted 27 September 2026
Volvo D5: 185 CV para el S60, V70, XC70 y XC90Autopista.es · Motoring press · published July 2005 · consulted 27 September 2026 · in Spanish
Fiabilité et pannes Volvo XC60 (2008-2017)Fiches-auto.fr · Other source · consulted 27 September 2026 · in French
Fiabilité et pannes Volvo V60Fiches-auto.fr · Other source · consulted 27 September 2026 · in French
Volvo XC90Wikipedia · Other source · consulted 27 September 2026 · in Spanish
Fiabilité Mercedes GLC (2015-2022)Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
Fiabilité et pannes Volvo S60Fiches-auto.fr · Other source · consulted 27 September 2026 · in French
Fiabilité et pannes Volvo XC60 (2017-)Fiches-auto.fr · Other source · consulted 27 September 2026 · in French