Cummins ISX12 XPI Fuel Injector | Alliant Power AP55103 Remanufactured

$947.00
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  • Core Charge - Cummins ISX12 (11.9L) on-highway six with the XPI common rail fuel system AP55103 (Refundable) - $305.00

View Core Charge & Return Policy

Remanufactured XPI common rail injector for the Cummins ISX12 — the 11.9L on-highway six. XPI runs far higher injection pressure than the older ISX platforms, which makes injector condition the difference between a truck that pulls clean and one that smokes, misses and burns fuel. These are rebuilt to original specification and end-of-line tested for flow and response.

On a working truck the usual tells are a rough idle at operating temperature, a cylinder-specific fault code, excessive crankcase or exhaust smoke, or fuel dilution in the oil. We can flow-test what you pull to confirm before you commit to a full set.

Part number AP55103
Brand Alliant Power
Condition Remanufactured — rebuilt to original specification and tested
Application Cummins ISX12 (11.9L) on-highway six with the XPI common rail fuel system
Shipping weight 3.3 lb
Warranty Alliant Power factory warranty on this unit. On anything we remanufacture in house: 1 year, 30 days on electrical components
Core charge Refundable $305.00, refunded in full when we receive your rebuildable core

Fits / Applications

  • Cummins ISX12 (11.9L) on-highway six with the XPI common rail fuel system
  • EPA 2010 and later ISX12 platforms — XPI, not the earlier ISX open-rail or CAPS systems
  • Vocational, regional-haul and refuse chassis running the ISX12
  • Six injectors per engine — see the set option below

Part Numbers & Interchange

Alliant Power AP55103  ·  AP system reference APP41110

Original-equipment numbers on this platform change with engine serial and emissions tier, so we do not publish a blanket interchange list that might send you the wrong part. Send us your engine serial number or VIN and we will confirm the exact match against your build before anything ships — that check is free and takes a few minutes.

Buying A Full Engine Set?

The ISX12 is a six, so a full engine takes six. We list the complete sets so you are not adding up quantities at checkout: set of 6. Ordering the set also gets the core deposit and the core return handled as one transaction instead of 6 separate ones.

Why do I see this common rail injector cheaper online?
Short answer: it is usually not the same part — and common rail does not forgive “close enough.” Read why ↓

Search any OE number and eBay, Amazon and a dozen storefronts will show it well under dealer cost, sold by outfits with no name, no address and no phone number. We lose business to those listings every week — and we see a lot of them come back through our shop. Here is what is actually different.

  • The part number proves nothing on its own. Counterfeit injectors and pumps are stamped with the same OE numbers as the real thing, in housings cast to look identical. The number in the listing title tells you what the seller claims it is, not what came off an OE line.
  • “Remanufactured” is not a regulated word. A genuine reman unit is stripped to bare components, has its wear parts replaced — nozzle, plunger and barrel, solenoid, seals — and is then run on a calibration bench until it meets the original flow and response spec. A cheap one is very often cleaned, resealed, painted and shipped. Both get called remanufactured.
  • No full teardown, so no idea what is worn. A proper rebuild means the unit comes apart completely and every part gets inspected and measured against spec — not just the ones that are obviously bad. Skip the teardown and you are reusing worn internals inside a freshly painted housing. It will run on the truck. It will not last.
  • No factory-spec bench load testing. A unit is not finished until it has been run under load on a test bench and made its numbers across the range, not just at one easy point. That bench time is most of what you are paying for. Sellers working on price cut it first, because nobody can see it in a photo.
  • The warranty has to be honored by someone. Everything we remanufacture in house carries a one-year warranty, with 30 days on electrical components. Parts we supply as an authorized dealer carry the manufacturer’s own warranty. Either way you call us, a real shop in California, and we sort it out. A marketplace warranty usually means shipping the part overseas at your own cost and hoping for a reply.
  • No core program. We credit your rebuildable core back in full. Discount sellers generally will not take one, so the gap narrows the moment you account for the core you are now stuck holding.
  • Common rail has no tolerance for “close enough.” These injectors meter fuel in fractions of a millisecond at pressures north of 20,000 psi, across multiple events per stroke. A nozzle or control valve that is merely near spec will not throw a code on the bench at idle — it shows up as a cylinder that runs hot, a balance rate that drifts, fuel in the oil, or a rail pressure fault six months out. And the labor to go back in is the same as it was the first time.

We are an authorized dealer and a working fuel-injection shop — we have been rebuilding and testing this hardware in Woodland since 1993, and the people who answer the phone are the people who run the benches. Not sure this is the right part for your engine? Call us with your serial number before you order and we will confirm it. Send your rebuildable core back and the core charge is refunded. And if a price somewhere else looks too good, call 530-668-0818 and we will tell you straight whether it is a deal or a problem.

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. Not sure which version your engine takes? Call us with your engine serial number before you order and we will confirm it — that check is free and takes a couple of minutes.

Not sure the injectors are the problem? We flow-test and diagnose injector complaints in-house — see our injector testing service before you buy a full set.

In Stock, Ships Free:
Ready to order online and ships free ground in the lower 48 states. A refundable $305.00 core deposit is added at checkout and refunded in full when we receive your rebuildable core. Questions on fitment? Call 530-668-0818.

Pricing covers the unit itself. Any applicable sales tax and the refundable core charge are additional; ground shipping in the lower 48 is free. Buying tax-exempt? Qualifying diesel repair shops, fleets, farms, and agricultural operations can purchase tax-free. Set up tax-exempt purchasing once and every qualifying order is tax-free going forward.

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Cummins ISX12 XPI Fuel Injector | Alliant Power AP55103 Remanufactured
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