This is the Bosch 0432191391, a new nozzle and holder assembly for the Cummins ISC 8.3L, the electronic C series that still uses a mechanical nozzle in the head. It replaces Cummins 3948523 and 3944211, and catalogs list Bosch 0432191500 as an alternate number. Opening pressure is 300 to 314 bar.

Mechanical injectors wear at the nozzle. A dribbling or stuck nozzle shows up as a miss, black or white smoke, fuel knock, hard starting or fuel in the oil. Pop test the old set before you condemn the pump. Replace them as a full set, one per cylinder, so every cylinder opens at the same pressure. It is not the common-rail ISC injector with a solenoid on top. It is also not Bosch 0432191426, another ISC 8.3L nozzle and holder that replaces Cummins 3948529, or Bosch 0432191601, the mechanical 8.3L injector that opens at 260 to 274 bar.

Specifications

Fits / Applications

• Cummins ISC 8.3L, engines that list injector 3948523 or 3944211
• Not for common-rail ISC engines with solenoid injectors
• Six per engine

Clean the bore and fit new seals with each injector. Tighten the hold-down and the fuel connections to the engine maker’s figures, bleed the system and check for leaks. Change the fuel filters at the same time.

Part Numbers & Cross Reference

Bosch 0432191391  ·  Bosch alternate 0432191500  ·  Cummins 3948523  ·  Cummins 3944211

Cross-reference numbers can change with engine serial, build year and emissions tier, so treat this list as a starting point. Send us your engine serial number and we will confirm the exact match against your build before anything ships. That check is free and takes a few minutes.

Frequently Asked Questions

What numbers does the Bosch 0432191391 replace?

Cummins 3948523 and 3944211. Catalogs also list Bosch 0432191500 as an alternate number for it.

Will it fit a common-rail Cummins ISC?

No. It is a mechanical nozzle and holder for the earlier ISC 8.3L. Common-rail ISC engines use a solenoid injector. Call 530-668-0818 with your engine serial number if you are not sure which you have.

Is the Bosch 0432191391 new or rebuilt, and is there a core?

It is a new Bosch nozzle and holder assembly, not a rebuild. It is sold outright, so there is no core to send back.

How does it differ from the other 8.3L injectors you list?

Bosch 0432191601 opens at 260 to 274 bar and replaces Cummins 3802753 and 3928228. Bosch 0432191628 and 0432191642 are mechanical 6CT injectors with their own Cummins numbers. This one is the ISC injector: it replaces Cummins 3948523 and 3944211 and opens at 300 to 314 bar.

Related Parts

• Cummins 6CT 8.3L C Series Mechanical Fuel Injector (3802486, 3928387) | Bosch 0432191628 New
• Cummins 6CT 8.3L C Series Mechanical Fuel Injector (3926120, 3802485) | Bosch 0432191642 New
• Cummins 6CTA 8.3L & Case IH Mechanical Fuel Injector (3802753, 3928228) | Bosch 0432191601 New
• Cummins ISC & ISL 8.9L HE300VG Turbo Actuator Kit | Holset 6382091HX Remanufactured
• Mechanical Diesel Injector Testing & Rebuild Service

Why Buy From Valley Fuel Injection

We are a diesel fuel-injection and turbocharger shop in Woodland, CA, rebuilding pumps, injectors and turbos on our own benches since 1993, not a drop-ship storefront. When you call, you talk to the people who test these units. We verify fitment against your engine serial, VIN or build date before anything ships, so the right part arrives the first time.