What This Sensor Does
The crankshaft position sensor is a magnetic pickup that reads a toothed target on the crank. The ECM uses that pulse train to know exactly where the crankshaft is, and it uses that position to time fuel injection. Lose the signal and the engine either will not start or drops to a limp condition running off the cam sensor alone.
This is the dedicated ISX-family crank position variant with a 3-pin oval connector. The connector body matches the factory harness plug, so no adapter or splicing is required on a straight replacement. The sensor housing is sealed against oil and washdown, and the mount is built to survive constant block vibration.
Symptoms that point here: extended cranking before it catches, a hot no-start that clears after cooling, a sudden shutdown at speed with a restart minutes later, and crank signal or timing fault codes logged with no mechanical cause. A cracked sensor body or chafed lead in the harness gives the same picture.
Why These Numbers Cross
4921599 is the headline number for this ISX-family crank position sensor. Cummins 4001902 and Fortpro F238875 appear in the interchange because they describe the same magnetic sensor element, the same 3-pin oval connector, and the same mounting form factor. Different catalogs, different label, same physical part in the bore.
Aftermarket and supplier numbers multiply for a couple of ordinary reasons. A part gets superseded during an engine family update, or a distributor assigns its own catalog number to a sensor it buys in. None of that changes the sensor. What matters is the element type, the connector, the pin count, and how the body sits in the block.
These numbers are listed for identification only. PartStop is not affiliated with, endorsed by, or authorized by any OEM manufacturer. Use the cross-reference to narrow the search, then confirm against the number stamped on the sensor you pull or against your engine serial number.
Check Before You Order
Pull the old sensor and read the number on the body. That is the most reliable check you have. If the label is oil-soaked or worn off, count the pins and look at the connector shape — this part uses a 3-pin oval plug. A round or 2-pin connector means you are looking at a different sensor entirely.
Verify your engine serial number before ordering. ISX, ISX15, QSX and QSX15 engines went into Freightliner Cascadia, Kenworth T680, Peterbilt 579, International ProStar and LT, Western Star and Volvo VNL chassis, and the chassis badge alone will not tell you which sensor the engine takes. Cross-reference is a starting point, not a fitment guarantee.
4921599 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 4921599. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| Cummins | 4001902 |
| Fortpro | F238875 |
Frequently asked questions
Is 4921599 the crank sensor or the cam sensor on an ISX?
This is the crankshaft position sensor, the dedicated ISX-family crank variant. The cam sensor is a separate part and is not interchangeable with it, even where the connectors look similar. If you are diagnosing a timing or no-start fault, confirm which sensor the code points to before you order.
Can I run the engine with a failed crank position sensor?
Some ISX-family engines will start and run on the cam sensor signal alone, but performance and fueling accuracy suffer and the engine may not restart once shut down. Treat it as a get-home condition, not a repair. Replace the sensor and clear the stored codes.
Will this drop in without rewiring?
The 3-pin oval connector is built to match the factory harness plug, so a straight swap needs no splicing or adapter. Check the harness lead for chafe and the connector pins for corrosion or spread terminals while you have it apart. Confirm fit against the number on the old sensor or your engine serial number.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
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Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.