Diagnostic Overview
MaxxForce fault code SPN 108 is commonly associated with barometric pressure or atmospheric pressure input, which can affect EGR and turbo calculations. If the ECM receives an inaccurate pressure value, it may miscalculate airflow, boost, and EGR flow. This can create drivability problems or set related EGR/air-management faults. Because the FMI is missing, the circuit direction must be confirmed with the complete diagnostic report.
Likely Causes
Faulty barometric pressure sensor, failed intake manifold pressure/temperature sensor depending on application, wiring issue, connector corrosion, incorrect sensor reading, or ECM reference voltage problem.
What To Check First
Compare key-on engine-off pressure readings to local barometric pressure, inspect sensor connectors, check 5-volt reference and ground, and look for related boost, MAP, or EGR codes.