I Built This Because My Dad's Truck Kept Breaking Down My dad runs a small trucking company in Texas. Last year, his 2018 Kenworth T680 threw SPN 3226 FMI 0 — NOx sensor circuit failure. The dealership quoted $650. He called me: "Can you find what this code means?" I searched Google. Results: two-line blurbs on generic sites. No technical depth. No repair cost estimates. No Spanish version for his Mexican driver. That's when I realized: truck drivers need a dedicated fault code datab...