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 3058 FMI 21: Meaning and Fix SPN 3058 FMI 21 indicates a data drift in the Engine Exhaust Gas Recirculation (EGR) System Monitor. This fault often emerges after an ECM software update or following the replacement of EGR components. It signifies that the EGR monitoring data has deviated below expected parameters, potentially … Read more
Diagnostic Code SPN 2631 FMI 8: Meaning and Fix SPN 2631 FMI 8 indicates the ECM has detected an abnormal frequency, pulse width, or period in the signal from the Engine Charge Air Cooler 1 Outlet Pressure sensor, reported in kPa. This fault commonly appears after aggressive turbocharger cleaning procedures or CAC sensor harness disturbance … Read more
Diagnostic Code SPN 2631 FMI 10: Meaning and Fix SPN 2631 FMI 10 indicates the Engine Control Module (ECM) has detected an abnormal rate of change in the charge air cooler 1 outlet pressure signal, exceeding the expected ramp rate. This fault commonly appears after a forced DPF regeneration when thermal expansion causes temporary sensor … Read more
Diagnostic Code SPN 1209 FMI 8: Meaning and Fix SPN 1209 FMI 8 indicates an abnormal frequency, pulse width, or period in the exhaust pressure sensor at the turbine intake of the turbocharger. This fault commonly appears after ECM updates or sensor replacements, especially in inline engines. Technicians might notice erratic readings during a diagnostic … Read more
Diagnostic Code SPN 1209 FMI 21: Meaning and Fix SPN 1209 FMI 21 signifies a low drift in the engine exhaust bank 1 pressure reading, specifically at the turbocharger intake. This fault often appears in inline engines or multiple bank engines where the measurement deviates from expected norms. A common scenario involves technicians encountering this … Read more
Diagnostic Code SPN 1209 FMI 20: Meaning and Fix SPN 1209 FMI 20 indicates the engine exhaust bank 1 pressure sensor signal has drifted above the expected calibrated range. This fault commonly appears after a forced DPF regeneration when soot loading or a partially blocked turbine inlet causes sustained high back pressure. Technicians frequently encounter … Read more
Diagnostic Code SPN 1209 FMI 19: Meaning and Fix SPN 1209 FMI 19 indicates the ECM has received erroneous or invalid CAN J1939 network data for Engine Exhaust Bank 1 Pressure at the turbocharger turbine intake. The fault reflects a data validity failure rather than a direct sensor hardware fault. This code commonly appears after … Read more
Diagnostic Code SPN 1209 FMI 17: Meaning and Fix SPN 1209 with FMI 17 indicates a lower-than-normal exhaust pressure at the turbocharger’s turbine intake on engine exhaust bank 1. Technicians often encounter this fault code after performing maintenance on the exhaust manifold or replacing turbocharger components. This code suggests a drop in pressure that, while … Read more
Diagnostic Code SPN 1209 FMI 15: Meaning and Fix SPN 1209 FMI 15 indicates the Engine Exhaust Bank 1 Pressure 1 is above the normal operating range. This gauge pressure measured at the turbocharger turbine inlet exceeds the calibrated limit set by the ECM. Technicians often encounter this fault after a forced DPF regeneration or … Read more
Diagnostic Code SPN 1209 FMI 10: Meaning and Fix SPN 1209 FMI 10 indicates an abnormal rate of change in exhaust backpressure measured at the turbine inlet of the Bank 1 turbocharger, expressed in kPa. The ECM detects pressure oscillations exceeding calibrated delta-pressure thresholds per unit time. This fault commonly appears during post-DPF regeneration cycles … Read more