The SPN 558 FMI 4 fault code indicates an issue with the Idle Validation Switch 1 Circuit, specifically that it has failed low. This diesel engine fault code suggests that the Engine Control Module (ECM) is detecting a low voltage condition in the circuit responsible for validating the throttle pedal's idle position. When this diagnostic trouble code appears, it typically points to an electrical p
read more
The SPN 558 FMI 3 fault code indicates an issue with the Idle Validation Switch (IVS) 1 circuit, specifically that it has failed high. This diesel engine fault code suggests that the Engine Control Module (ECM) is detecting a higher than expected voltage in the IVS circuit, which can affect throttle position readings and engine idling behavior. What SPN 558 FMI 3 Means The SPN 558 FMI 3 diagnostic
read more
The SPN 558 FMI 2 fault code indicates that the Idle Validation Switch (IVS) inputs are reversed. This diesel engine fault code is triggered when the Engine Control Module (ECM) detects that the signals from the IVS are not in the expected configuration, suggesting a wiring issue or component failure.What SPN 558 FMI 2 MeansThe SPN 558 FMI 2 fault code specifically relates to the Idle Validation S
read more
The SPN 556 FMI 9 fault code indicates a communication issue where the J1939 RC message from the transmission retarder is missing. This diesel engine fault code suggests that the Engine Control Module (ECM) is not receiving the expected data from the transmission retarder, which can affect vehicle performance.
What SPN 556 FMI 9 Means
SPN 556 FMI 9 is a diagnostic trouble code that signifies a lo
read more
The SPN 527 FMI 9 fault code is a diesel engine diagnostic trouble code indicating that the J1939 CCVS (Cruise Control Vehicle Speed) message is missing. This code suggests a communication issue within the J1939 network, affecting the transmission of vehicle speed data to the ECM (Engine Control Module).What SPN 527 FMI 9 MeansWhen the SPN 527 FMI 9 fault code appears, it indicates a disruption in
read more
The SPN 525 FMI 19 fault code indicates an issue where the transmission gear selection switch is reporting implausible engine brake stage requests. This diesel engine fault code suggests a communication problem between the transmission and the engine brake system, often due to electrical issues or software discrepancies.What SPN 525 FMI 19 MeansThe SPN 525 FMI 19 fault code signifies that the Engi
read more
The SPN 525 FMI 9 fault code indicates a missing J1939 powertrain message related to the transfer case or PTO system. This diesel engine fault code suggests that the Engine Control Module (ECM) is not receiving the expected data from the PTO control module, which can affect the operation of the power take-off system.What SPN 525 FMI 9 MeansWhen the SPN 525 FMI 9 fault code is active, it means that
read more
The SPN 525 FMI 7 fault code indicates an internal error reported by the transmission gear selection switch. This diesel engine fault code suggests that the transmission control system is experiencing issues with the gear selection switch, which is crucial for proper gear engagement and transmission operation.What SPN 525 FMI 7 MeansThe SPN 525 FMI 7 fault code represents a problem within the tran
read more
The SPN 524 FMI 9 fault code is a diesel engine fault code indicating that the J1939 ETC2 message is missing. This diagnostic trouble code suggests a communication issue between the Engine Control Module (ECM) and other components on the J1939 data link, such as the Transmission Control Module (TCM). When this code is active, it means the ECM is not receiving expected data, which can affect engine
read more
The SPN 523 FMI 19 fault code indicates an erratic signal from the J1939 Transmission Current Gear. This diesel engine fault code suggests that the ECM is receiving inconsistent data regarding the transmission's current gear position, which can affect vehicle performance and drivability. What SPN 523 FMI 19 Means The SPN 523 FMI 19 fault code represents an issue with the transmission control syste
read more
