Comprehensive SAE J1939 fault codes for diesel and gas engines. Find SPN and FMI diagnostic trouble codes for electronic engine controllers, temperature, fluid pressure, turbocharger, fuel systems, and combustion parameters used in heavy-duty trucks, agricultural, and construction equipment.
Diagnostic Code SPN 94 FMI 8: Meaning and Fix This fault indicates the ECM detected an abnormal signal frequency, pulse width, or period from the fuel delivery pressure sensor (SPN 94). The sensor typically outputs a PWM signal between 50-500 Hz. A deviation outside the expected range triggers FMI 8. This code commonly appears after … Read more
Diagnostic Code SPN 94 FMI 21: Meaning and Fix SPN 94 FMI 21 indicates a low drift in the engine’s fuel delivery pressure. This fault generally manifests when the data received by the ECU drifts lower than the expected range. A common scenario is after a fuel filter replacement, where technicians might encounter this code … Read more
Diagnostic Code SPN 94 FMI 20: Meaning and Fix This fault indicates the ECM detected fuel delivery pressure (gauge) consistently above the calibrated maximum threshold for the given operating conditions. In practice, this code often surfaces after a fuel filter replacement that introduced air, or when a high-pressure pump overshoots due to a stuck regulator. … Read more
Diagnostic Code SPN 94 FMI 19: Meaning and Fix SPN 94 FMI 19 indicates the ECM has received erroneous or invalid network data for Engine Fuel Delivery Pressure via the J1939 CAN bus, rather than a direct sensor hardware failure. The fault targets data integrity at the message layer. This code commonly appears after replacing … Read more
Diagnostic Code SPN 94 FMI 10: Meaning and Fix The SPN 94 FMI 10 code indicates an abnormal rate of change in engine fuel delivery pressure. This issue often arises in scenarios like post-ECM replacement or following a forced DPF regeneration. The fuel system’s pressure change is critical for engine performance and efficiency. Technicians frequently … Read more
Diagnostic Code SPN 5357 FMI 8: Meaning and Fix SPN 5357 FMI 8 indicates the ECM has detected abnormal frequency, pulse width, or period in fuel injection quantity commands affecting multiple cylinders simultaneously. The injector control signals deviate beyond calibrated tolerances, triggering a system-level fault. This code commonly appears in MAN TGX and Deutz TCD … Read more
Diagnostic Code SPN 5357 FMI 21: Meaning and Fix SPN 5357 FMI 21 indicates a drift in the fuel injection quantity data affecting multiple cylinders. This is commonly seen after ECM recalibrations or when replacement parts are not calibrated correctly. Technicians frequently encounter this code following a forced DPF regeneration, which can disrupt fuel system … Read more
Diagnostic Code SPN 5357 FMI 20: Meaning and Fix This fault indicates the ECM detected the actual fuel injection quantity for multiple cylinders has drifted above the commanded value, often due to injector wear or fuel pressure sensor drift. Technicians frequently encounter this after a DPF regeneration, where high fuel demand exposes inconsistent delivery across … Read more
Diagnostic Code SPN 5357 FMI 19: Meaning and Fix SPN 5357 FMI 19 indicates the ECM has received erroneous network data related to fuel injection quantity across multiple cylinders via the J1939 CAN datalink. Per SAE J1939-73, FMI 19 specifically flags corrupt or invalid data received from a networked control module. This fault commonly appears … Read more
Diagnostic Code SPN 5357 FMI 15: Meaning and Fix SPN 5357 with FMI 15 indicates an above-normal fuel injection quantity error for multiple cylinders. This typically arises in scenarios where there’s a fuel injection calibration error, often noticed after ECM replacement or reprogramming. Technicians might encounter this fault when the engine runs at high load … Read more