Cummins ISX12 425ST2
Built: 2014-2015 · Series: ISX12
More machines from model year 2014
Not the right version? The data comes from vehicle registers holding many near-identical versions side by side. Photograph the data plate — we read make and type from it. Open the scanner e-mail address required
Cummins ISX12 – the 11.9-litre six-cylinder for distribution, tippers and natural-gas trucks (2013–2016): 310 to 500 hp, diesel and ISX12 G
The ISX12 is the smaller sister of the ISX15: an 11.9-litre in-line six that grew out of the ISX11.9 in 2013 and was built until 2016, when the X12 replaced it. Cummins aimed it at regional haulage, tippers, concrete mixers, refuse trucks and coaches – duties where the weight of the 15-litre engine is unnecessary but a 9-litre engine would be too small. The engine shares its architecture and aftertreatment (particulate filter, SCR, cooled EGR) with its big brother.
Read on 3 more paragraphs
The number in the name is the output in hp; suffixes such as ST (SmartTorque), EV, R or MC mark torque curves and calibrations, and RV stands for motorhome chassis. The register lists 31 versions with 315 to 479 hp at 1,700 to 2,100 rpm and 1,150 to 1,650 lb-ft (1,559 to 2,237 Nm) of torque, in every case reached at 1,200 rpm; certifications cover model years 2013 to 2016, all with single-stage turbocharging, service class HHDD and in two cases urban bus.
A special feature: six of the 31 versions run on natural gas – that is the ISX12 G, a spark-ignited gas engine with throttle-body injection that Cummins Westport introduced in 2013 for CNG and LNG trucks. It was the first natural-gas engine of the 12-litre class in North America and made tractor units of up to 36 t possible without diesel; the 400 hp rating did not quite match the strongest diesel sibling but was enough for regional work.
On used diesel versions, particulate filter, SCR dosing and EGR valve are what count; on the gas engines, spark plugs, ignition coils and the fuel system with tanks that have their own inspection intervals.
Sources: SpecCodex register, model data: Cummins ISX12 (EPA-Zertifizierungsdaten), Cummins Motoren (manufacturer), EPA-Zertifizierungsdaten Motoren
Technical data
Engine
| Engine code | 3711; FR20588; 4591:FR20718correct |
|---|---|
| Engine family | ECEXH0729XAE; GCEXH0729XAEcorrect |
| Engine families | ECEXH0729XAE; GCEXH0729XAEcorrect |
| Fuel | dieselcorrect |
| Rated output | 308 kW (= 413 bhp)correct |
| Rated speed | 1,977 rpmcorrect |
| Maximum torque | 1,650 ft·lbfcorrect |
| Speed at max. torque | 1,200 rpmcorrect |
| Operating cycle | dieselcorrect |
| Injection | electronic direct injectioncorrect |
| Aspiration | single-stage turbocorrect |
Origin and approval
| Built from | 2014correct |
|---|---|
| Built to | 2016correct |
| Model year from | 2014correct |
| Model year to | 2016correct |
Other data
| Application | HHDDcorrect |
|---|
Frequently asked questions
How much power does the Cummins ISX12 425ST2 have?
The Cummins ISX12 425ST2 delivers 308 kW.
When was the Cummins ISX12 425ST2 built?
Production years: 2014-2015.
What to check before buying
- Match the data plate against the order: frame size, mounting and rating have to agree.
- For used units, ask about winding condition and bearing play.
- Ask about parts availability for this series — the running costs hang on it.
A general list for this type of machine — no substitute for an inspection or an appraiser.
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This page carries 19 individual figures for this model. They come from 2 recorded sources; every figure can be traced there. What we cannot document is not here — we leave gaps open rather than estimate them.
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Other models in this series
ISX12 310
ISX12 320R
ISX12 330
ISX12 330R
ISX12 330ST
ISX12 350
ISX12 350R
ISX12 350ST
ISX12 370
ISX12 370EV
ISX12 385
ISX12 385CC
Sources: US EPA — engine certification data (retrieved August 2026) · How we check the data
Diesel engine in 3D section
Turn the model, look inside and click an assembly — each one is explained.
Parts for this engine (32)
Manufacturer part numbers from the official EPA documentation. No prices or availability — those come from the supplier.
| Part number | Description | Manufacturer |
|---|---|---|
| 4307496 | Ammonia | Cummins |
| 2872784 | Charge Air Cooler Temperature | Cummins |
| 4307110 | Compressor Inlet Temperature | Cummins |
| 4954905 | Coolant Temperature Sensor;Coolant Temp Sensor;Coolant Temperature Sensor;Engine Out NOx Sensor 2;Coolant Temperature Sensor;Oil Temperature Sensor;Oil Temperature Sensor;Coolant Temperature Sensor;Coolant temp sensor | Cummins |
| 2871960 | Diesel Particulate Filter Pressure | Cummins |
| 4307101 | Aftertreatment Temperature Sensor | Cummins |
| 4307103 | Aftertreatment Temperature Sensor | Cummins |
| 4928594 | Exhaust Manifold Pressure;EGR Orifice Pressure Sensor;EGR pressure sensor | Cummins |
| 2872279 | Crankshaft Position Sensor;Camshaft Position Sensor;Crankshaft Position Sensor;Crankshaft Position Sensor;Camshaft Position Sensor;Camshaft Position Sensor;Engine Camshaft;Engine Crankshaft;Engine Crankshaft;Engine Crankshaft Position Sensor;Engine Crankshaft Position Sensor;Engine Crankshaft | Cummins |
| 2872944 | Engine Out NOx Sensor 1 | Cummins |
| 2872945 | Engine Out NOx Sensor 1 | Cummins |
| 4326470 | Engine Out NOx Sensor 1 | Cummins |
| 4326862 | Engine Out NOx Sensor 1 | Cummins |
| 4326870 | Engine Out NOx Sensor 1;Engine Out NOx Sensor | Cummins |
| 2872424 | Exhaust Gas Recirculation Pressure | Cummins |
| 2872858 | EGR Out Temperature Sensor;Intake Manifold Temp Sensor;EGR Out Temperature Sensor;EGR Out Temperature Sensor;Intake Manifold Temp Sensor;EGR temp sensor | Cummins |
| 4307166 | Exhaust Gas Recirculation Pressure | Cummins |
| 2897581 | Fuel Pressure | Cummins |
| 4921519 | Hydrocarbon Doser Fuel | Cummins |
| 2872943 | NOx Sensor Selective Catalytic Reduction | Cummins |
| 2872946 | NOx Sensor Selective Catalytic Reduction | Cummins |
| 2897307 | NOx Sensor Selective Catalytic Reduction | Cummins |
| 4326472 | Tailpipe NOx Sensor | Cummins |
| 4326864 | Tailpipe NOx Sensor | Cummins |
| 4326874 | Tailpipe NOx Sensor | Cummins |
| 4307100 | Aftertreatment Temperature Sensor | Cummins |
| 4307102 | Aftertreatment Temperature Sensor | Cummins |
| 4307345 | Turbocharger Speed Sensor | Cummins |
| 3781358 | Turbolader | Cummins |
| 3781359 | Turbolader | Cummins |
| 3795155 | Turbolader | Cummins |
| 3795156 | Turbolader | Cummins |
Source: 2013 Model Year On-Highway Heavy-Duty Engine Certification Data
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