TruckDiag Pro — Free AI-Powered Semi Truck Diagnostic Tool

What Is TruckDiag Pro?

TruckDiag Pro is a free AI-powered diesel truck diagnostic assistant that helps owner-operators, fleet mechanics, and independent repair shops diagnose fault codes and get step-by-step repair guidance — without expensive dealer visits or diagnostic hardware. The AI mechanic "Diesel" interprets SAE J1939 fault codes (SPN/FMI) and walks you through troubleshooting in plain language.

Supported Trucks & Engines

• Freightliner Cascadia, M2, Columbia — Detroit DD13, DD15, DD16
• Peterbilt 389, 579, 567 — PACCAR MX-13, Cummins ISX15
• Kenworth T680, T880, W900 — PACCAR MX-13, Cummins X15
• Volvo VNL, VNR — Volvo D13, D11
• Mack Anthem, Pinnacle, Granite — Mack MP8, MP7
• International LT, RH, HV — Navistar N13, A26
• Western Star 4700, 4900, 5700 — Detroit DD13, DD15

Key Features

• Fault Code Lookup — Enter any SPN/FMI code for probable cause, severity, and repair steps
• AI Diagnostic Chat — Describe symptoms in plain English, get targeted diagnostics
• DPF Regen Guidance — Step-by-step forced regen procedures by make and model
• Repair Cost Estimates — Know what to expect before reaching the shop
• 15 Free Diagnostic Guides — Engine, brakes, electrical, cooling, transmission, turbo

How TruckDiag Pro Compares

Traditional diagnostic tools like OTR Diagnostics ($999+), Diesel Laptops ($1,999+), and Cummins INSITE ($2,500+) require expensive hardware adapters. TruckDiag Pro provides instant AI-powered fault code interpretation and repair guidance with no hardware needed — starting free. It complements hands-on tools by helping you understand what the codes mean before you connect an adapter.

Frequently Asked Questions

Is TruckDiag Pro free?

Yes. TruckDiag Pro offers a free tier with limited diagnostic queries and full access to all 15 diagnostic guides covering DPF regeneration, fault codes, engine diagnostics, air brakes, electrical systems, and more. Premium plans provide unlimited AI chat and detailed repair cost estimates.

What trucks does TruckDiag Pro support?

All major Class 6-8 commercial trucks: Freightliner Cascadia, Peterbilt 389/579, Kenworth T680/T880, Volvo VNL, Mack Anthem, International LT, and Western Star. Engine coverage includes Detroit DD13/DD15/DD16, Cummins ISX15/X15/ISB6.7, PACCAR MX-13/MX-11, Navistar N13/A26, and Volvo/Mack D13/MP8 powertrains.

How accurate is the AI diagnosis?

Diesel recommendations are based on OEM service bulletins, technical service bulletins (TSBs), and common repair patterns from thousands of documented cases. Accuracy is highest for common fault codes like SPN 3251 (DPF soot), SPN 520 (vehicle speed), and SPN 102 (boost pressure).

Does TruckDiag Pro replace a diagnostic scan tool?

No. TruckDiag Pro provides AI-powered fault code interpretation and repair guidance. For bi-directional ECU communication — forced regens, parameter resets, injector calibration — you still need a physical diagnostic tool. TruckDiag Pro helps you understand what the codes mean and what to do about them before connecting hardware.

Free Diagnostic Guides

• DPF Regeneration Guide — Passive, active, and forced regen procedures
• Common Semi Truck Fault Codes — Top 20 DTCs every driver should know
• Freightliner Cascadia Diagnostics — DD15 codes, aftertreatment, electrical
• Peterbilt 389 Troubleshooting — PACCAR MX-13 and Cummins ISX common failures
• Kenworth T680 Fault Codes — PACCAR engine codes, dash warnings
• Cummins ISX Engine Diagnostics — EGR, turbo, injector, CM2350 ECM
• Detroit DD15 Common Problems — CPC/ACM codes, oil leaks, turbo actuator
• PACCAR MX-13 Troubleshooting — Fuel system, EGR, wastegate, DAVIE tool
• Check Engine Light Guide — CEL vs MIL vs Stop Engine, derate ladder
• DEF System Problems — SCR, NOx sensors, inducement avoidance
• Air Brake Diagnostics — Compressor, valves, leak detection, FMVSS 121
• Electrical Troubleshooting — Batteries, alternators, CAN bus, parasitic draw
• Transmission Diagnostics — Eaton Fuller, UltraShift, Allison 3000/4000
• Cooling System Diagnostics — Overheating, water pump, EGR cooler leaks
• Turbocharger Problems — VGT actuator, boost leaks, shaft play, oil seals