Detroit Diesel Aftertreatment Diagnostics

Detroit Diesel Aftertreatment Diagnostics

Modern Detroit Diesel engines use complex emissions systems, including the DPF, SCR, and EGR. If your truck is showing fault codes or entering derate mode, you need a way to quickly scan, diagnose, and fix the issue before it costs you downtime.

Here’s how to run aftertreatment diagnostics using our Diesel Diagnostic Laptop Kit, which comes preloaded with the tools needed for Detroit engines.

🧰 What You’ll Need:

  • The Diesel Diagnostic Laptop Kit
    (includes preloaded software, cables, and adapter—no subscriptions or VIN locks)

  • Access to your truck’s 9-pin or 6-pin diagnostic port

🔌 Step 1: Connect to the Truck

  1. Plug the RP1210 adapter (included) into the truck’s diagnostic port and your laptop.

  2. Power up the laptop and open the Detroit diagnostic program included in the kit.

  3. Connect to the ECM and confirm the VIN and engine model match.

⚙️ Step 2: Open the Aftertreatment System Menu

Once connected, go to the aftertreatment section. This gives you access to key systems:

  • Diesel Particulate Filter (DPF)

  • Selective Catalytic Reduction (SCR)

  • Exhaust Gas Recirculation (EGR)

  • DEF tank, sensors, and lines

🚨 Step 3: Read SPN/FMI Fault Codes

  • Scan for fault codes related to soot levels, derates, NOx sensor failures, and more.

  • Common Detroit emissions-related codes include:

    • SPN 5246 – Emissions derate active

    • SPN 3719 – DPF soot load too high

    • SPN 4364 – NOx sensor performance issue

📊 Step 4: Monitor Live Sensor Data

Use the included software to track:

  • Exhaust gas temps

  • DEF dosing rates

  • Soot accumulation

  • Sensor readings (NOx, temp, pressure)

Live monitoring helps pinpoint which system is failing and whether the truck is ready for a regen.

🔥 Step 5: Regeneration Control

  • View past regen history and see if previous regens failed.

  • Manually initiate a parked or forced regen from your laptop.

  • Ensure regen completes and that soot levels drop back to safe levels.

💧 Step 6: SCR and DEF Diagnostics

You’ll be able to check:

  • DEF levels and quality

  • Dosing module performance

  • NOx sensor data pre/post SCR

Use this info to determine whether the SCR system is causing derate or fault codes.

♻️ Step 7: EGR System Checks

  • Inspect EGR valve movement

  • Measure EGR cooler efficiency

  • Watch for blockages or valve errors causing excessive soot

🧪 Step 8: Run Component Tests

The software lets you manually test:

  • NOx sensors

  • DEF dosing valves

  • Pressure sensors

  • EGR valve actuation

You’ll also get guided instructions to replace or reset components if needed.

📝 Step 9: Document Your Work

Create and save a report inside the software with:

  • Fault codes found

  • Actions taken (regen, reset, tests)

  • Repaired or replaced components

Perfect for warranty claims, service history, or customer reports.

✅ Simplify It All with One Kit

Instead of piecing together software and cables, just grab our all-in-one Diesel Diagnostic Laptop Kit. It’s:

  • Fully preloaded

  • Ready to plug and scan

  • Compatible with all major Detroit Diesel engines

  • Backed by a 2-year warranty and 30-day free-return policy

👉 Stop guessing and start fixing—get your kit now

Would you like an infographic or printable step-by-step sheet for this one?

Back to blog