If you’ve recently completed a repair or resolved a warning light on your semi truck, the last thing you want is lingering fault codes that won’t clear. Clearing codes is an essential step in diesel diagnostics—and with the right diesel laptop scanner, it’s quick and easy.
Here’s how you can clear fault codes on a semi truck using a professional diesel diagnostic tool like the ones we offer at DieselScanners.com.
🚛 Why Fault Codes Appear
Fault codes are triggered when your truck’s ECM (engine control module) detects a parameter outside of its normal operating range. This could be from:
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A failed sensor
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A disconnected component
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Low voltage
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A temporary glitch
Even after fixing the root issue, the fault code can stay “active” or stored in memory until it’s manually cleared.
🧰 What You’ll Need
To clear codes, you'll need:
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A rugged diesel diagnostic laptop (e.g., Dell CF-31 or Getac V110)
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A NEXIQ USB-Link 2 or 3 adapter
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Diagnostic software like JPRO, Diesel Tech, or OEM-specific tools (like Cummins Insite or Detroit DDDL)
All of these are available in our complete kits at DieselScanners.com—plug-and-play and pre-loaded.
✅ Step-by-Step: How to Clear Fault Codes
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Connect the Adapter
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Plug your adapter into the truck’s diagnostic port (usually 9-pin).
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Connect the other end to your diesel laptop.
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Open Your Diagnostic Software
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Launch JPRO, Diesel Tech, or your OEM software.
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Identify the Vehicle
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The software will auto-detect the VIN, engine type, and active modules (ECM, TCM, ABS, etc.).
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Read the Codes
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View active and inactive (historical) fault codes.
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Make sure the underlying issue is resolved first.
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Clear Codes
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Select the “Clear Fault Codes” option.
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Confirm the action—some systems require ignition cycles or specific engine conditions.
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Verify
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Re-scan the system to ensure codes are gone.
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Drive the truck or let it idle briefly to check if they reappear.
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⚠️ What If Codes Won’t Clear?
If a code is "active," your laptop scanner may not allow it to clear until the issue is fixed. In that case:
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Recheck the wiring and component
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Look for live data out of range
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Refer to troubleshooting steps inside your software
🧠 Pro Tip
Use freeze frame data and live parameters in your software to pinpoint the issue before clearing the code. Guessing can waste time and money.
💻 Get a Pre-Loaded Diagnostic Kit
Don’t waste time with cheap code readers. Our diesel laptop kits are professional-grade, ready to use out of the box, and include:
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Lifetime tech support
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Training videos
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Full software suite with coverage for Freightliner, Kenworth, Volvo, International, Peterbilt, and more
🛒 Browse Kits at DieselScanners.com
📦 Optional Add-ons You’ll Love
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Dell Rugged Laptop Upgrade – Faster, brighter screen, longer battery life
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1-Year Accident Protection Plan – Accidental drops, cracks, spills? You’ll only pay a small deductible for laptop replacement (software stays covered). Must be added within 30 days of purchase.