Freightliner, Western Star and Sterling Heavy Duty Diagnostic Scanners

Written by the YOUCANIC technicians in Towson, Maryland, from the UCAN-HD-A coverage database and our own shop work. Updated October 24, 2026.

A Freightliner is two sets of electronics in one truck: the chassis modules Freightliner builds in, and an engine from Detroit Diesel, Cummins or the MBE family that carries its own control module, aftertreatment module and service routines. A code reader from the parts store sees neither properly, and the dealer laptop that does is a subscription per engine maker. The UCAN-HD-A is the scanner we use for Class 4 to 8 work: it identifies the truck, reads the chassis entry for the Cascadia, M2, SD and FL models, and then opens the engine maker entry for the regeneration, injector and DEF routines that get a derated truck back on the road. Western Star and Sterling trucks ride on the same Daimler electronics and the same engines, so the same kit covers them. Pick by what you need to do, then check the connector note.

Which Scanner Do I Need For A Freightliner?

CLASS 4 TO 8 TRUCKS, BUSES, ENGINES AND EQUIPMENT

UCAN-HD-A

Full system heavy duty scanner on SAE J1939, J1708 and J1587 with a wireless VCI and the 9 pin, 6 pin and OBD2 connectors in the case. Reads every module the truck reports, runs forced DPF regeneration, injector cut off, injector codes, DEF and EGR tests on the engine entries, and graphs live data. Free updates, no subscription. The tool to own if you keep a Freightliner, Western Star or Sterling working.

PICKUPS, VANS AND CARS

UCAN-II Pro, new or open box

Full system, bidirectional, lifetime free updates, with a built in TPMS module. The scanner for the Ford, RAM, GM and Sprinter pickups and vans that run alongside the big trucks. It does not speak J1939 or J1708, so it is not the tool for the Class 8 tractor; for a mixed fleet you want both.

What The UCAN-HD-A Does On A Freightliner

• ✓ Chassis entry for the Freightliner models and years in the database: ECU Information, Read Codes, Erase Codes and Live Data, listed by model with the engine type on each (Cummins, Detroit Diesel MBE, John Deere, GM, PSI and the 4P10 and 4M50 engines in the light models)
• ✓ Western Star entry: ECU information, read codes, erase codes and live data on the Engine control module for the 4700, 4800, 4900, 5700, 47X, 49X, 57X and 6900, with year entries from before 2001 to 2022 and newer
• ✓ Detroit Diesel engines (DD13, DD15, DD16 and the MBE family): the Detroit entry lists the MCM motor control module in its EPA07, EPA08, EPA10 and 2.1 versions, the ACM aftertreatment control module, the CPC common power control and the SAM cabin and chassis modules, with the special functions DPF, Injector cut off, Injector Codes and Limit
• ✓ Cummins engines (ISX, ISB, ISC, ISL, ISM and the X and B families): the Cummins entry lists Cylinder Cutout Test, Aftertreatment Diesel Particulate Filter Regeneration, the DEF doser override and heater tests, the EGR valve tests, Features and Parameters, Trip Information and Maintenance Monitor
• ✓ Forced DPF regeneration, stationary and driving, with soot load, exhaust temperature and differential pressure on screen, plus ash service regeneration after a filter cleaning
• ✓ Injector cut off to find the weak or dead cylinder, cylinder balance, and injector code entry after a replacement
• ✓ SCR and DEF: dosing tests, heater tests, fluid level reset and NOx monitoring on the engine entries that list them
• ✓ Live data from several modules graphed at once, PID merge, recording and playback, and PDF reports from the tablet
• ✓ Wireless VCI, so you run the test from the cab or the engine bay without a cable back to the tablet

Service Functions By Job On A Freightliner

On the tablet you pick the make entry, then the model or engine family, then the module, the function category and the routine. Freightliner and Western Star hold the chassis level entries; the engine service functions live under the engine maker. These are the routines the coverage database lists, grouped by the job you are doing. Names are as they appear on the tablet. Coverage varies by model year, engine and ECM software, so check yours before you order.

What The Scanner Sees On A Freightliner

Three entries pulled from the coverage database. The chassis makes list codes and live data by model and year; the engine makers list the modules and the service routines on top of that.

Symptom, Then The Routine That Fixes It

• DPF lamp, high soot load or a derate on a Cascadia with a DD13 or DD15: the DPF routine in the Detroit entry (MCM and ACM), with soot, temperature and differential pressure on the live data screen.
• A cylinder that sounds dead on a Cummins ISX or ISB in an M2 or a Columbia: Cylinder Cutout Test in the Cummins entry, one injector at a time.
• New injectors in a Detroit Diesel engine: Injector Codes in the Detroit entry, then Injector cut off to confirm each cylinder contributes.
• DEF quality, doser or heater fault on a Cummins: Diesel Exhaust Fluid Doser Pump Override Test, Doser System Heater Test and the Dual Doser Override Test in the Cummins entry.
• EGR codes on a Cummins: EGR Valve Test, EGR Valve Actuator Test and EGR Delta Pressure Auto Zero Test in the Cummins entry.

Frequently Asked Questions

Will it run a forced DPF regeneration on my Cascadia with a DD15?

Yes. The regeneration runs from the Detroit Diesel entry, where the MCM and ACM modules carry the DPF special function, and the UCAN-HD-A shows soot load, exhaust temperature and differential pressure while it runs. Confirm your engine family and ECM version in the coverage checker first.

My M2 106 has a Cummins ISB. Which entry do I use?

Both. The Freightliner entry gives you the chassis codes and live data for the M2 106, and the Cummins entry gives you the engine: Cylinder Cutout Test, Aftertreatment Diesel Particulate Filter Regeneration, the DEF doser tests and the EGR tests on the ISB families the database lists.

Which connector does my truck have, and is it in the box?

The kit includes the 9 pin Deutsch, the 6 pin Deutsch and the OBD2 connector. The 9 pin is the common one on the Cascadia, Columbia, Century, Coronado and M2 era trucks, the 6 pin is on the older J1708 trucks, and some light models use OBD2.

Does it cover Western Star and Sterling?

Western Star has its own entry with the 4700, 4800, 4900, 5700, 47X, 49X, 57X and 6900 and year entries from before 2001 to 2022 and newer. Sterling is not a separate entry; those trucks share the Freightliner chassis family and the same engine entries, so check your Sterling by VIN with support before you order.

Can it change the road speed limiter or flash the ECM?

It does not flash an ECM. On supported engines the Cummins entry lists Features and Parameters, and the UCAN-HD-A can view and set the road speed governor and idle settings there; dealer password protected parameters stay with the engine maker's software.

How do I know my exact truck and function are covered?

Use the coverage checker by make, model and engine, or call 1-888-959-4265, Monday to Friday 9 AM to 4 PM Eastern, with the VIN and the engine, and a technician will tell you plainly. If it does not do what you need, we will say so. Every scanner also comes with 31 day returns, no questions asked.

Running Detroit or Cummins power? See the Detroit Diesel and Cummins engine pages. For other makes see the scanners by make hub, the service functions explained one job at a time, and the step by step repair guides on youcanic.com.