What causes a SPN 632 code?

SPN 632 can be triggered by several issues — see the verified probable causes and step-by-step diagnostics shared by mechanics and owners on OBDIY.

Can I drive with a SPN 632 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 632 active.

How do I fix SPN 632?

Follow the step-by-step diagnostic on this page, then read the verified fixes contributed by other Heavy Truck owners — the answer marked "Verified Cause" worked for the original poster.

OBDIY

J1939 SPN

SPN 632

J1939 SPN 632 — Engine Management parameter

What it means

Fuel Shutoff Valve Control Circuit. The ECM has detected a fault (open circuit, short, or improper current) in the circuit that controls the engine fuel shutoff solenoid.