What CAT Injector Do I Need? Breaking Down 10R0958, 10R1273, 10R0957, 10R0955 for Your C15 or 3406E

What CAT Injector Do I Need? Breaking Down 10R0958, 10R1273 & 10R0955 for Your C15,3406E, and C15 ACERT

🧩 What Do These Numbers Even Mean? 

The numbers (like 10R0955 or 10R0958) are Caterpillar’s part numbers. But what most folks care about is that last two-digit number — 55,57, 58, or 73 — because that’s what some use to identify the injector

Here’s the quick breakdown:

• 10R0955 ("55s")

  • Commonly used in marine or industrial applications.

  • Supports higher horsepower builds (800–1000+ HP).

  • Should be paired with a marine camshaft (800HP or 1000HP cam) and a large turbo

  10R0957 ("57s") / 10R8501

  • Stock in many 550HP Cat 3406E/C15 engines (e.g., 6NZ).

  • Best suited for stock 550HP or mildly tuned engines (manifold, tune, 78MM turbo).

  10R0958 ("58s") / 10R8502

  • Slightly larger than 57s.

  • Found in some 550HP Cat 3406E/C15 models.

  • Can support larger turbos (80MM / 1.45 AR) and horsepower in the 700–750HP range with proper tuning.

  10R0959 ("59s")

  • Largest stock Caterpillar injector available.

  • Capable of supporting well over 1000HP with proper supporting mods.

  10R1273 ("73s")

  • CAT C15 Acert injectors.

  • Not interchangeable with non-Acert 3406E/C15 engines.

  • Different injection cycle, spray angle  and trim coding make them incompatible.

🧪 How Do I Know If My Injectors Are Bad?

You don’t need a lab coat — just look for these signs:

✅ Excessive white smoke on cold starts
✅ Fuel in the oil
✅ Rough idle or miss
✅ High EGTs under throttle
✅ Poor MPG, even after tuning
✅ Hard starts or no starts

You can also do a cylinder cutout test or have your shop run injector balance rates. But if your CAT’s running weird, it's usually fuel or air — and injectors are often the culprit.

📋 What Info Do I Need to Give Texas Truck Market for the Right Injectors?

To make sure you get the right injectors the first time, here’s what we’ll ask:

• Engine serial number (starts with MBN, 6NZ, etc.)

• Current injector part number (if you know it)

• Turbo setup (stock, aftermarket, compound?)

• Desired horsepower

• Any ECM tuning or upgrades done already

You give us that, we’ll get you dialed in — no guessing.

🛠️ What Happens If You Don’t Enter Trim Codes?

Bad things:

• Poor fuel economy

• Rough idle

• High EGTs

• Misfires

• Potential engine damage over time

Basically, you’re flying blind without them — the ECM won’t know how to adjust for each injector’s specific flow pattern.

💡 Pro Tip:

When ordering new injectors from Texas Truck Market, make sure to:

• Ask if trim codes are included (ours always are ✅)

• Save that code! You’ll need it at install time.

Want help programming your new injector trim codes? Give us a shout at 832-867-3345, and we’ll walk you through it or connect you with a tech who can.

Let me know if you want an image explaining trim codes next!

📞 Still Have Questions?

Whether you’re building a towing workhorse or a dyno-crushing highway runner, the team at Texas Truck Market is here to help you get the right injectors, turbo, and tuning setup.

📲 Call or text us at 832-867-3345
🛒 Or shop online at texastruckmarket.com