What This Sensor Does
This is an exhaust gas temperature sensor. It threads into a boss in the exhaust or EGR path and feeds a resistance signal back to the ECM. The ECM uses that temperature to manage EGR flow, time the regen cycle, and protect the aftertreatment hardware from overtemp. No signal, no trusted temperature, and the engine starts derating.
The probe is 304 stainless, built to sit in hot gas stream without scaling off at the tip. The connector is a sealed two-pin, which matters more than most people think — these live under the chassis in road spray, salt, and constant vibration. Water in the pins reads as an open circuit and sets the same code as a dead element.
Application coverage runs across Cummins ISX15 and X15 in Class-8 trucks — Cascadia, T680, 579, ProStar and LT, VNL — plus Cummins ISF3.8 and the 6.7L ISB and QSB. Confirm by engine serial number, not by truck model, because EGT sensor locations and lengths vary across the aftertreatment layouts.
Why These Numbers Cross
2872858 and 4627861 are engine-manufacturer side numbers that cover the same EGT probe with the same thread, probe length, and two-pin connector. One supersedes or sits alongside the other depending on build date and the aftertreatment supplier used on that engine family. The sensing element and calibration curve are what matter, and they match.
PAI 050730 is the aftermarket catalog number for the same sensor. 577.90532 and AM57790532 are the same number in two formats — one written with the European dot separator, one with the alphanumeric prefix used by other distributors. If your search landed on either style, you are looking at a single part, not two.
Numbers crossing does not mean the sensor bolts into your truck. Two engines in the same family can run different probe lengths depending on where the sensor sits relative to the DPF or the turbo outlet. Pull the old sensor, read the number stamped on the hex or the connector body, and check it against this list.
How These Fail
Most failures are mechanical, not electrical. The lead wire chafes where it runs along the frame rail or the DPF shield, or the harness pigtail cooks against an uninsulated pipe. You get an intermittent open that only shows up hot. Wiggle-test the harness with the engine at temperature before you condemn the sensor itself.
The other common one is the probe seizing in the boss. Heat cycling welds the threads in place and the hex rounds off or the body snaps during removal. Soak the threads, heat the boss, and back it out slow. Have an anti-seize rated for exhaust temperature on hand for the new one, and torque to the figure in your service manual.
2872858 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 2872858. 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 |
|---|---|
| Cross-Reference | PAI 050730, 577.90532, AM57790532, 4627861 |
Frequently asked questions
Is 2872858 the same sensor as PAI 050730?
They cross to the same exhaust gas temperature sensor — same thread, same probe style, same two-pin sealed connector. PAI 050730 is the aftermarket catalog number for that part. Confirm against the number on your old sensor or your engine serial number before you order, since probe length can vary by position in the aftertreatment.
Why do I see 577.90532 and AM57790532 listed separately?
Same number, two formats. One uses the dot separator, the other an alphanumeric prefix used by different distributors. Searching either one should bring you to the same EGT sensor. Treat them as a single reference, not two different parts.
Will replacing this sensor clear my derate?
It will if the fault code points specifically at the EGT circuit and the sensor or its wiring is the failure. Check the harness for chafe and the connector for water intrusion first — a bad pigtail sets the same code. After replacement, clear codes and run the engine to temperature to confirm the reading tracks correctly.
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