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ENGINE FAMILY DOSSIER

Mercedes-Benz OM654 Engine Family

OM654 family fuel architecture, cylinder layout, displacement class, application scope and measurement-led diagnostic framework.

QUICK TECHNICAL ANSWERS

What concrete information can you get from this page?

Verified application example: OM 654

VERIFIED FACTModel / system fact

Mercedes-Benz identifies OM 654 as the four-cylinder diesel member of a new engine family and describes it as its first all-aluminium four-cylinder diesel.

FAULT SEPARATIONWhen a symptom appears

For low power/rail faults, capture low-side supply, rail target/actual and injector corrections at the same load.

FIRST MEASUREMENTBefore replacing parts

Capture cold-engine sensor rationality, then observe EGT/NOx/EGR behavior through a controlled warm-up.

Primary source: Mercedes-Benz Group – The future of the diesel engine, OM 654

Engine identity

Manufacturer group
Mercedes-Benz
Engine family
OM654
Fuel / energy architecture
Turbo diesel
Cylinder layout
4
Displacement class
1597-1950 cc
Vehicle scope
passenger van

OM654; diesel_turbo; 4 cylinder/layout; 1597-1950 cc class

What to verify before ordering parts

  • Do not treat the family name and sub-code as identical; separate production period and market variant.
  • Emissions level, turbo/injection hardware and sensor/actuator generation can vary inside one family.
  • Transmission, hybrid system, ECU software and vehicle class can change the service procedure.

Diagnostic approach

Narrow faults by combining mechanical condition, air/fuel flow, pressure, temperature, lubrication, electrical supply and ECU commands rather than using the DTC label alone. Comparing loaded live data with idle measurements is particularly valuable for intermittent and performance faults.

Diesel / heavy-duty chain

Treat common-rail pressure, low-pressure supply, turbo air path, EGR, DPF/SCR and engine protection/derate behaviour as one interacting chain. Aftertreatment faults can affect torque request and field performance.

J1939 SPN/FMI →

ENGINE DIAGNOSTIC FLOW

Measurement sequence

  1. Confirm exact engine code and application by VIN/model year/market.
  2. Check power supply and ECU communication.
  3. Capture air, fuel/energy, temperature and lubrication data at the same load.
  4. Compare commanded values with physical result.
  5. Verify under the same load after repair.

Source-verified powertrain relationships

The relationships below come only from existing curated relation records; they are not exact vehicle/model fitment claims.

curated_relation9G-Tronic 725.0

Mercedes diesel longitudinal

OEM EVIDENCE DOSSIER

Verified technical facts and application boundary

  1. Mercedes-Benz identifies OM 654 as the four-cylinder diesel member of a new engine family and describes it as its first all-aluminium four-cylinder diesel. [S1]
  2. The OM 654 manufacturer description lists steel pistons, stepped combustion bowls, NANOSLIDE cylinder coating and fourth-generation common-rail injection. [S1]
  3. The exhaust aftertreatment elements are packaged directly on the engine; Mercedes-Benz also describes multiway EGR combining cooled high- and low-pressure EGR. [S1]

Verified application matches

The matches below are published only within the stated market, model-year and evidence scope. Fitment is not extrapolated to uncited variants.

Engine: OM 654

Evidence scope: manufacturer engine-family description; calibration varies by application

System architecture and component relationships

  • Diagnostic architecture separates low/high-pressure fuel, turbo/air path, high+low-pressure EGR and the engine-mounted DPF/SCR/NOx/EGT aftertreatment chain.
  • For EGR faults, correlate air mass, boost, HP/LP EGR commands and exhaust pressure/temperature behavior.
  • Because aftertreatment is close-coupled, sensor temperature ordering and dosing behavior should be time-correlated with the actual thermal event.

DTC / SPN-FMI / symptom discrimination map

  • For low power/rail faults, capture low-side supply, rail target/actual and injector corrections at the same load.
  • For EGR/boost faults, branch MAF, boost, EGR command and charge-air/exhaust leak or restriction tests separately.
  • For NOx/SCR faults, correlate EGT sequence, upstream/downstream NOx and dosing command rather than condemning the catalyst from one sensor code.

Measurement and diagnostic strategy

  • Capture cold-engine sensor rationality, then observe EGT/NOx/EGR behavior through a controlled warm-up.
  • Do not invent exact pressure thresholds without the applicable service procedure; use target-versus-actual deviation and independent supply verification.
  • After repair, recreate comparable temperature/load and verify derate, fault state and PID normalization together.

Exact pinouts, torque values, pressure thresholds or service limits are published only when explicitly verified by the applicable OEM service source.

Evidence provenance and primary sources

  1. Mercedes-Benz Group – The future of the diesel engine, OM 654 · OEM-primary · 2026-08-15
  2. Mercedes-Benz Group – Sustainability presentation: OM 654 · OEM-primary · 2026-08-15
ENGINE DIAGNOSTIC DEPTH

Architecture evidence package

  • Fuel path is separated into low-side supply → high-pressure pump → rail → injectors; air path into MAF/MAP → turbo control → intake manifold.
  • On turbo-petrol architecture, load calculation, boost target/actual, lambda/fuel trim, ignition and knock control are compared in the same event window.

Live data to capture for this family

  • Freeze frame: first/last fault time, RPM, load, vehicle speed, system voltage, core temperatures and companion DTCs.
  • Live data: rail target/actual, low-side supply where supported, MAF/MAP, boost target/actual, EGR command/feedback.
  • Aftertreatment: DPF differential pressure, soot/ash calculations, EGT chain, NOx in/out and SCR/DEF dosing enable.
  • Live data: calculated load, MAP/boost target-actual, throttle angle, lambda/O2, STFT/LTFT, ignition advance and knock retard.

Engine measurement chain

  1. 1) Match vehicle/generation/market/powertrain/driveline identity to the source record; family name alone is not fitment evidence.
  2. 2) Preserve freeze frame and companion DTCs before clearing; make the first-fault condition reproducible.
  3. 3) Verify power/ground and network communication under load; do not decide from key-on static measurement alone.
  4. 4) Compare commanded air/fuel/pressure with an independent physical result; separate sensor bias from real performance loss.
  5. 6) After repair, recreate the same load/temperature and verify DTC state, live-data deviation and user symptom together.

This section is an architecture-safe diagnostic layer derived from family identity; application-specific OEM limits are shown only when a verified evidence dossier exists.

Engine root-cause split

  • If rail pressure is low, separate low-side supply from high-pressure generation: when physical low-side supply is healthy but rail cannot follow target, regulation/pump/injector-leakage branches gain weight.
  • For low boost, do not jump to turbo replacement: separate MAF/MAP plausibility, charge leak, VGT/wastegate command and exhaust backpressure at the same load point.
  • On lean/misfire/boost complaints, align fuel trim, lambda, ignition retard and boost deviation on one time base to separate air leak, fuel-delivery and ignition causes.

Related technical centers

DTC Academy → · Vehicle Universe →

Sources & freshness

Sources & freshness

Exact technical values, prices and failure rates are not invented without verified vehicle/manufacturer evidence.

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