Detailed guide for SPN 4360 FMI 2
Back to top ↑What this fault means
SPN 4360 FMI 2 indicates an erratic, intermittent or implausible temperature signal in the applicable SCR or aftertreatment temperature circuit. Exact sensor naming and location vary by manufacturer.
The SCR system depends on reliable exhaust temperature information to determine when dosing and catalyst-efficiency calculations are valid.
What you may notice
Possible symptoms include aftertreatment warnings, unstable temperature readings, dosing-related faults or other SCR efficiency codes. An intermittent connection may cause the fault to appear only after vibration, heat or a longer drive.
What to check first
Inspect the temperature sensor connector for loose terminals, corrosion and heat damage. Follow the harness and pay particular attention to areas near exhaust components, brackets and vibration points.
Use live data to watch the temperature signal. A reading that suddenly jumps, drops out or disagrees significantly with nearby exhaust-temperature sensors can help locate an intermittent problem.
Wiring before parts
Perform a wiggle test where appropriate while monitoring the signal. Check circuit continuity and terminal tension using the manufacturer's procedure.
Do not replace the sensor solely because the code names a temperature circuit. Wiring and connector problems are common causes of intermittent electrical faults.
After repair, verify that the temperature signal changes smoothly as the exhaust warms and cools and that related SCR faults do not return.
Mechanic community notes for SPN 4360 FMI 2
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