Detailed guide for SPN 2623 FMI 3
Back to top ↑What SPN 2623 FMI 3 means
SPN 2623 identifies accelerator pedal position channel 2.
FMI 3 indicates the APP2 signal voltage is above the expected range or shorted toward a high source.
Navistar documentation describes the fault as APP2 signal out of range high.
What you may notice
The malfunction indicator lamp may illuminate immediately.
Because multiple accelerator-pedal channels are used for safety and plausibility checking, the ECM may limit torque or alter throttle response when the channels disagree.
What to check first
Inspect the accelerator pedal connector for moisture, corrosion, bent pins or damaged terminals.
Check the APP2 circuit for a short to power and verify the sensor ground.
Use live diagnostic data to compare both accelerator pedal channels through the full pedal travel.
Important
Do not replace the pedal assembly until wiring and connector faults have been ruled out.
Mechanic community notes for SPN 2623 FMI 3
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