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 2623 FMI 21: Meaning and Fix SPN 2623 FMI 21 indicates the second channel of the redundant accelerator pedal position sensor is reporting a voltage or percentage value that has drifted below the minimum calibrated threshold, typically less than 0.5 volts or 2.5%. This fault commonly appears after a battery jump-start with … Read more
Diagnostic Code SPN 2623 FMI 20: Meaning and Fix SPN 2623 FMI 20 identifies that the secondary output signal of Accelerator Pedal #1 redundant sensor has drifted abnormally high beyond calibrated thresholds. The ECM compares both sensor channels continuously; when Channel 2 diverges upward from Channel 1 beyond tolerance, this fault is logged. This commonly … Read more
Diagnostic Code SPN 2623 FMI 19: Meaning and Fix SPN 2623 FMI 19 indicates a network data error for the second sensor output of Accelerator Pedal #1. This fault code often appears after a vehicle experiences erratic engine response or reduced torque output, particularly when a redundant sensor system is in place. Technicians frequently encounter … Read more
Diagnostic Code SPN 2623 FMI 17: Meaning and Fix SPN 2623 FMI 17 indicates that Accelerator Pedal #1 Channel 2 output is valid but below the normal operating range. This means the sensor signal is present but lower than expected, often due to a weak 5V reference, high resistance, or a sensor drift. In practice, … Read more
Diagnostic Code SPN 2623 FMI 16: Meaning and Fix SPN 2623 FMI 16 indicates that the secondary output channel of the redundant accelerator pedal position sensor #1 has reported a valid but excessively high percentage signal, exceeding the calibrated upper threshold defined by SAE J1939 and OEM ECM parameters. This fault commonly appears after accelerator … Read more
Diagnostic Code SPN 2623 FMI 10: Meaning and Fix This diagnostic trouble code signals that the Engine Electronic Controller (EEC) has detected an implausible rate of change in the voltage signal from the accelerator pedal position sensor’s second channel. This fault often appears after a technician replaces the ECM without reprogramming the pedal calibration, leading … Read more
Diagnostic Code SPN 1347 FMI 21: Meaning and Fix SPN 1347 FMI 21 flags a sustained low-drift condition in the Engine Fuel Pump Pressurizing Assembly #1 feedback signal, indicating the common-rail pressure build-up has fallen below the ECM-expected threshold without a hard electrical failure. This fault commonly appears on Bosch CP3 and CP4 high-pressure pump … Read more
Diagnostic Code SPN 1326 FMI 8: Meaning and Fix SPN 1326 with FMI 8 indicates an abnormal frequency in the misfire rate for engine cylinder 4. This condition is particularly evident after events like a forced DPF regeneration, where combustion parameters are altered. Affected engines often exhibit rough idling, decreased power output, and increased emissions. … Read more
Diagnostic Code SPN 1326 FMI 21: Meaning and Fix SPN 1326 FMI 21 indicates that the Engine Cylinder 4 misfire rate, measured as a percentage over engine cycles defined by SPN 6394, has drifted below expected operational thresholds. The ECM interprets this sustained low-rate deviation as a combustion anomaly. This fault commonly appears during cold-start … Read more
Diagnostic Code SPN 1326 FMI 20: Meaning and Fix SPN 1326 FMI 20 indicates a high data drift in the misfire rate of engine Cylinder 4. This error often arises after an ECM software update or following the replacement of ignition components. Technicians may notice this fault code during routine diagnostics, especially when misfires lead … Read more