SPN 3058 FMI[10,16,18] Engine Faults Explained

SPN 3058 means that the EGR system monitor has a problem. Each FMI is different as shown below.

FMI 10 – Abnormal rate of change

FMI 16 – Data valid but above normal – moderately severe

FMI 18 – Data valid but below normal – moderately severe

FMI 0 – Data Valid But Above Normal Operational Range (Most Severe Level)
This FMI indicates that the EGR mass flow rate is higher than the acceptable range. Check for issues with the EGR valve, such as sticking or not closing completely, and inspect the EGR cooler for clogging or damage. Additionally, look for any vacuum leaks, damaged wiring, or faulty sensors.

FMI 1 – Data Valid But Below Normal Operational Range (Least Severe Level)
This FMI suggests that the EGR mass flow rate is lower than the acceptable range. Inspect the EGR valve for sticking or not opening completely, and check for clogging or damage in the EGR cooler. Also, check for vacuum leaks, damaged wiring, or faulty sensors.

FMI 2 – Data Erratic, Intermittent, or Incorrect
This FMI indicates that the EGR mass flow rate data is inconsistent or incorrect. Inspect the EGR valve and EGR cooler for proper operation, and check the wiring and connections to the EGR sensors. Look for loose connections, corrosion, or damaged wires.



Things to check:
motor control module software version
EGR sensor
Clean exhaust gas recirc system


The Exhaust Gas Recirculation (EGR) system monitor is a component of a vehicle’s onboard diagnostic system (OBD-II) that checks the functionality and efficiency of the EGR system. The EGR system helps reduce nitrogen oxide (NOx) emissions by recirculating a portion of exhaust gases back into the engine’s combustion chamber. This reduces peak combustion temperatures, which in turn reduces the formation of NOx.

The EGR system monitor performs several tasks, including:

  1. Monitoring the position of the EGR valve: The ECU or ECM checks whether the EGR valve is functioning properly by comparing its expected position with its actual position. If there is a significant discrepancy, a diagnostic trouble code (DTC) may be triggered.
  2. Checking EGR flow: The EGR system monitor evaluates the flow of exhaust gases through the EGR system. If the flow is insufficient or excessive, a DTC may be triggered.
  3. Evaluating EGR system components: The EGR system monitor checks the functionality of various components, such as the EGR valve, EGR control solenoid, and EGR temperature sensor. If any of these components are not functioning properly, a DTC may be triggered.
  4. Monitoring EGR system efficiency: The EGR system monitor evaluates the overall efficiency of the EGR system by comparing the NOx levels before and after the EGR process. If the system is not reducing NOx emissions effectively, a DTC may be triggered.




I found a safe spot to pull over, just past the intersection near an all-too-familiar coffee shop. The scent of roasted beans wafted through the air, but it was the least of my concerns. I retrieved my tablet from the glove compartment, which was about the size of a small pizza box, and began searching for the meaning behind SPN 3058.

From what I could gather, the error was related to the fuel and air metering system. Specifically, it pointed to an imbalance between the air and fuel ratio, which could lead to increased emissions and reduced engine performance. My heart sank a little. Emission problems weren’t something you could just wish away with a hard reset.

I ventured out of the cab and popped the hood, which released with a familiar sturdy click. The engine, usually a vision of mechanical order, now felt like a puzzle with a missing piece. I checked the air intake system, tracing the path to the turbocharger, which was about the size of a large grapefruit. All connections seemed secure, and there was no obvious sign of damage.

The problem was likely deeper – a sensor issue, perhaps, or something wrong with the fuel injectors. These were tiny components, no bigger than a few inches each, but crucial to the delicate balance of the engine’s operation. With a sigh, I closed the hood, the metal echoing a dull thud as it shut.