A 2009 International Durastar bucket truck with a Maxxforce 7 engine and Allison automatic transmission, with approximately 100,000 miles and 7,000 operating hours, experienced a power reduction and an emission fault indicator illuminating around 20 mph. The fault codes retrieved were SPN 3985 FMI 9 and SPN 1552 FMI 2, both listed as inactive. While the initial diagnosis pointed towards a potential EGR valve issue due to the SPN 1552 FMI 2 code (Anomalous read, EGR top valve), and SPN 3985 FMI 9 (Cab HVAC System Controller – Abnormal update rate), the truck exhibited no typical symptoms of EGR cooler failure, such as coolant loss or water in the exhaust. The HVAC system also functioned normally, casting doubt on the relevance of the SPN 3985 code. After restarting the truck the following day, the issue reoccurred after a couple of miles, further complicating the diagnosis. This scenario necessitates a deeper understanding of diagnostic trouble codes (DTCs), specifically focusing on Spn 2003 Fmi 9, to effectively pinpoint the root cause of the problem.
While the original error codes didn’t include SPN 2003 FMI 9, this code often arises in similar situations with Maxxforce engines. SPN 2003 FMI 9 signifies a problem with the “Exhaust Gas Recirculation (EGR) Differential Pressure Sensor.” FMI 9 indicates an “Abnormal Update Rate,” suggesting the sensor is not communicating correctly with the engine control module (ECM). This faulty communication can lead to inaccurate EGR flow readings, causing the ECM to adjust engine performance, resulting in reduced power.
Several factors can contribute to SPN 2003 FMI 9. A common culprit is a malfunctioning EGR differential pressure sensor itself. Damaged wiring or connectors in the sensor circuit can also disrupt communication. Additionally, a clogged or restricted EGR system, including the EGR valve or cooler, can impact pressure readings and trigger the fault code. Finally, issues within the ECM itself, although less common, can’t be ruled out.
Troubleshooting SPN 2003 FMI 9 typically involves a systematic approach. First, visually inspect the EGR differential pressure sensor and its wiring for any obvious damage. Next, using a diagnostic scan tool, monitor the sensor’s readings and compare them to manufacturer specifications. This will help determine if the sensor is providing accurate data. If the sensor readings are erratic or out of range, replacing the sensor is often the next step. If the sensor appears to be functioning correctly, further investigation into the EGR system and its related components is necessary. This may involve checking for restrictions in the EGR cooler or valve. Consulting a qualified technician with experience in Maxxforce engines is recommended for accurate diagnosis and repair.
In conclusion, while the initial fault codes didn’t directly point to SPN 2003 FMI 9, understanding this code and its implications is crucial for troubleshooting power loss issues in Maxxforce engines. A systematic diagnostic approach, combined with a thorough understanding of the EGR system, is essential to identify the root cause and implement the necessary repairs. By addressing the underlying issue, the truck’s performance can be restored, and future problems can be prevented.
