Makes and models we could tie to this engine family through the vehicle maker's own literature and/or NHTSA recall filings. "Years documented" means the years those sources cover. It isn't a complete production span, and not every vehicle of that model has this engine.
See every family side by side on the By vehicle page.
04Emissions eras (EGR, DPF, SCR)
Era dates are Cummins' on-highway emissions steps in North America. A given truck or bus can carry an engine built to the previous standard for a while after a change, so go by the engine dataplate, not just the model year.
1998–1999
ISC (8.3) and ISL (8.9) launch as electronic Interact System engines; the ISL used Cummins' CAPS fuel system.[1,2]
2007
Cummins Particulate Filter (DPF) added for EPA 2007.[8,11]
2010
EPA 2010: SCR/DEF added; ISC8.3 and ISL9 switch to the XPI common-rail fuel system with cooled EGR and a single VGT.[8,12]
2017
ISL9 renamed L9, with Single Module aftertreatment and new ratings.[4,3]
2024
EPA 2024 L9. Cummins lists an X10 for EPA 2027 fire and transit applications; New Flyer's 2025 powertrain sheet shows the X10 alongside the L9.[5,9,21]
05Common issues, in plain English
Patterns documented by the sources below, not a prediction for any one engine. Diagnose before buying parts and follow the engine and vehicle makers' service information.
Remote fuel-filter hose leaks on the L9
Applies to L9 with a remote stage-2 fuel filter (RV chassis, transit buses, medium-duty trucks)
The L9 has been the subject of repeated safety campaigns over the hoses that run to a remotely mounted fuel filter. In 2021 Cummins recalled engines whose hose between the fuel pump and remote filter head could leak. In 2025 and 2026 further campaigns covered hoses that can separate from their fittings, leaking fuel and stalling the engine, across Freightliner Custom Chassis, Spartan, New Flyer and Freightliner M2 vehicles.
Because several campaigns overlap, run both a VIN search and an engine-serial-number check: a vehicle repaired under one campaign may still be due for a later one.
What to watch for
Diesel smell or wetness around the remote fuel filter.
Open campaigns on both the chassis VIN and the engine serial number.
Applies to DPF-equipped ISL/L9 in school and transit buses
The same soot-burning problem described for the B-series applies to the L-series in stop-and-go buses. Cummins' school-bus guidance (limit idling, give the engine highway time, enable Stay Warm) is written for both families.
Applies to Model-year 2010–2015 vehicles with Cummins engines
The 2018 EPA/CARB emissions recall for SCR catalysts that wore out early covered about 60 Cummins engine families across medium- and heavy-duty vehicles and some buses. See the full explanation on the B-series page.
1. Search the vehicle. Enter the 17-character VIN at nhtsa.gov/recalls. That finds recalls filed by the vehicle maker (the truck, bus or chassis builder), such as Freightliner, Blue Bird or Nissan.[38]
2. Search the engine. Recalls Cummins files against its engines are equipment recalls. Their campaign numbers contain an "E" (for example 18E-081) and they follow the engine serial number (ESN), so they may not show up in a VIN search. On the same NHTSA page, search equipment/manufacturer for Cummins, or open a campaign number directly, then compare its build dates and part numbers with your engine. For a definite answer, give the ESN from the engine dataplate to a Cummins-authorized service location.[24,39]
3. Bulletins. TSBs for medium- and heavy-duty vehicles appear on NHTSA as manufacturer communications when the maker files them; we don't copy their text. Year/make/model shortcuts: 2024 New Flyer XD402021 GILLIG Low Floor
Safety recalls we verified on NHTSA
Engine campaigns filed by Cummins plus the vehicle-maker campaigns that go with them. More L9 hose campaigns exist for other chassis; the application table links the ones we verified. Each one was confirmed in NHTSA's campaign records on 2026-10-19; summaries are in our own words. It's not a complete list for any vehicle.
Certain L9 engines sold for Pierce fire trucks · Flexplate capscrews
Flexplate capscrews might not have been tightened properly; the flexplate could separate and stall the engine. Dealers replace the flexplate and capscrews.[32]
Certain L9 and ISX12 engines · High-pressure fuel rail
A sealing washer might not seat in its bore, letting the high-pressure fuel rail leak, which is a fire risk. Dealers inspect threads and lines and replace the rail as needed.[33]
Engine recall (filed by Cummins) · about 45,334 units
L9 engines with a remote stage-2 fuel filter · Fuel hose to remote filter
The hose between the fuel pump and the remote filter head could leak fuel (fire risk). Dealers replace the hoses. Vehicle-maker versions include 21V-556 (Freightliner Custom Chassis), 21V-566 (Spartan RV Chassis) and 21V-601 (Kenworth/Peterbilt).[26]
Engine recall (filed by Cummins) · about 2,922 units
Remote fuel-filter hoses can pull off their fittings, leaking fuel and stalling the engine. Dealers replace the hoses; NHTSA lists owner letters as expected Nov 20, 2026. Freightliner's matching vehicle campaign is 26V-660.[30]
Engine recall (filed by Cummins) · about 39,052 units
ISB6.7, ISC8.3, ISL9, ISX11.9 and ISX15 shipped Sep - Dec 2010 · DOC/DPF V-band clamps
Clamps joining the inlet and outlet sections of the oxidation catalyst/particulate filter could let go and vent hot exhaust early, a fire risk. Cummins worked through the vehicle makers to reach owners.[35]
Engine recall (filed by Cummins) · about 11,860 units
Certain ISB6.7, ISL9, ISX12 and ISX15 engines · Engine control module
The ECM could short and blow a fuse, stalling the engine without warning. Dealers replace the ECM. Freightliner/Western Star/Thomas counterpart: 15V-620.[36]
Engine recall (filed by Cummins) · about 805 units
Certain X15, X12, L9 and B6.7 engines · Engine control module
An internal short in the ECM can stall the engine. Dealers replace the ECM. Thomas Built's school-bus counterpart is 22V-553.[37]
Engine recall (filed by Cummins) · about 12,196 units
07Marine cousins
Marine versions are sold separately as the QSC8.3 and QSL9, with their own ratings (Cummins lists 490–600 hp for the QSC8.3 and 290–410 hp for the QSL9). They aren't covered here.[22,23]
SRCSources
Accessed October 2026. Numbers in brackets throughout the page point here. Brand names are used descriptively.