Diagnostic Overview
Mack fault code P113000 is generally an emissions or sensor-performance fault that can contribute to derate depending on engine calibration. It may involve NOx, air-handling, or fuel/combustion monitoring. Because Mack code definitions can vary by model year, the exact description should be confirmed by VIN in Tech Tool.
Likely Causes
Faulty sensor; wiring or connector issue; exhaust leak; air-handling problem; fuel-system problem; calibration-specific emissions fault.
What To Check First
Confirm the exact Tech Tool definition, then inspect the named sensor or system, compare live data, and check related active codes.