SPN 3510 FMI 3 — Sensor supply voltage 1 high

SPN 3510 identifies the parameter the control module is monitoring — sensor supply voltage 1 high. FMI 3 is the failure mode the module logged against it. Both numbers matter: the same SPN with a different FMI is a different repair.

Multiple sensor codes set at once.

• Shorted sensor pulling the 5V rail
• Chafed harness to battery voltage
• ECM connector corrosion

• Unplug sensors one at a time to find the short
• Inspect the harness for chafe points
• Check ECM connector pins

Work the list in order and record the readings. Confirm the fault with live data before any part is ordered — a code names a circuit, never a failed component.

Short distance only

Multiple sensors are unreliable right now. Short trip home only, and expect derates.

• Replacing the sensor named in the SPN before checking its wiring, connector and ground.
• Clearing the code and handing the truck back without reproducing the operating condition that set it.
• Reading one code out of a set instead of finding which fault occurred first.

Get a shop involved when the fault comes with a red lamp or a shutdown timer, when the checks above all pass and the code returns, or when the repair needs an aftertreatment service tool, a forced regen, or engine internals. Nothing on this page is a substitute for OEM service literature or a qualified technician on the truck.

Enter this code in Blue Collar AI diagnostic support with the engine and the symptoms and you get the test sequence in order, per-truck history so repeat faults are visible, and a printable work order. Aftertreatment codes are covered in depth in the Aftertreatment Mastermind training. It is all in Truck Commander at $14.99 a month.