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SPN 632 — Fuel Shutoff Valve #1

Safe to driveTo the nearest safe stop

J1939 code SPN 632. Below — how the fault is worded at the factory by SITRAK, and what the second half of the code (FMI) means in the standard.

SITRAK

FMI 3Low-pressure solenoid valve short circuit to power supply
FMI 4Low-pressure solenoid valve short circuit to ground
FMI 31Fuel injection duration exceeds expected value

What FMI means in J1939

SPN 632 FMI 3632/3 · 632.3voltage above normal or shorted high
SPN 632 FMI 4632/4 · 632.4voltage below normal or shorted to ground
SPN 632 FMI 31632/31 · 632.31condition exists (see manufacturer description)

Can I keep driving

Safe to drive. Below — how much time you have and what happens if you keep going.

What happens if you keep driving

Time you have: To the nearest safe stop

Fuel is not arriving in the right amount or at the right pressure. It shows up first on climbs and under load.

You will most likely stall out on the road, and may not restart on the shoulder. A clogged filter or water in the tank you can nurse to a shop; a failing injection pump you cannot.

This is an electrical fault: an open, a short or a bad contact in the sensor circuit. The value it measures is most likely fine. You can drive. But until the circuit is repaired this system runs blind and cannot warn you about a real failure.

What to check on the spot

Check the fuel filter and water trap, drain the water. In cold weather, suspect fuel waxing.

Nearby: fuel

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