SAE J1939 fault codes for liquid and gaseous fuel systems. Includes SPN and FMI diagnostic codes for fuel consumption, fuel economy, fuel injection, gaseous fuel pressure, alternate fuel systems, and fuel leakage detection on heavy-duty engines.
Diagnostic Code SPN 230 FMI 16: Meaning and Fix SPN 230 FMI 16 indicates that the total idle fuel used parameter for gaseous fuel systems has exceeded the normal operating threshold, classified as moderately severe. The ECM logs accumulated idle fuel consumption data and compares it against calibrated limits. This fault commonly appears in CNG-powered … Read more
Diagnostic Code SPN 230 FMI 15: Meaning and Fix SPN 230 FMI 15 indicates that the idle fuel consumption is above normal operating range, though data is valid. This issue often arises after sensor recalibration or an ECU update, leading technicians to question fuel mapping accuracy. In practice, this code may appear when a vehicle … Read more
Diagnostic Code SPN 230 FMI 10: Meaning and Fix SPN 230 FMI 10 indicates the total idle fuel used (gaseous) is changing at an abnormal rate, typically due to a faulty fuel mass flow sensor or corrupted ECM calibration. This code commonly appears after a forced DPF regeneration on natural gas engines, where the ECM … Read more
Diagnostic Code SPN 230 FMI 6: Meaning and Fix SPN 230 FMI 6 signals a current above normal or grounded circuit condition on the sensor measuring total idle fuel used (gaseous). This code frequently appears after an ECM swap when a pin is misaligned or a harness chafes against the frame rail, causing a direct … Read more
Diagnostic Code SPN 230 FMI 14: Meaning and Fix SPN 230 FMI 14 indicates a special instruction condition related to the Total Idle Fuel Used in gaseous engines. This fault is often encountered after replacing the ECM, where recalibration of fuel parameters is necessary. In practice, this code might appear when a vehicle experiences irregular … Read more
Diagnostic Code SPN 1442 FMI 6: Meaning and Fix SPN 1442 FMI 6 indicates the ECM detected current exceeding the normal range on the Engine Fuel Valve 1 Position sensor circuit, typically due to a short to ground or a failed actuator. In practice, this fault commonly appears after a technician accidentally pinches the harness … Read more
Diagnostic Code SPN 1442 FMI 9: Meaning and Fix This fault indicates the Engine Control Module detects irregular signal refresh intervals from the gaseous fuel valve position sensor. The feedback circuit should provide continuous position data for precise fuel metering control. Technicians commonly encounter this code after CNG system maintenance when connector terminals develop corrosion … Read more
Diagnostic Code SPN 1442 FMI 7: Meaning and Fix SPN 1442 with FMI 7 concerns the mechanical non-responsiveness of a gaseous fuel valve, affecting the fuel flow regulation to the engine. A common occurrence of this fault is during irregularities in engine fuel demand, especially following maintenance that involves the fuel system. Technicians often encounter … Read more
Diagnostic Code SPN 1442 FMI 5: Meaning and Fix SPN 1442 FMI 5 indicates the ECM detects insufficient current flow or open circuit in the engine fuel valve 1 position feedback circuit. This fault commonly appears during CNG/LNG system commissioning when technicians disconnect position sensor harnesses without powering down the ECM, or after moisture infiltration … Read more
Diagnostic Code SPN 1442 FMI 4: Meaning and Fix The SPN 1442 FMI 4 fault code is triggered when the voltage at the Engine Fuel Valve 1 Position sensor is below normal or shorted low. This condition can lead to improper metering of gaseous fuel to the engine, resulting in performance issues. Technicians often encounter … Read more