What causes a SPN 3951 code?

SPN 3951 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 3951 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3951 active.

How do I fix SPN 3951?

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 3951

J1939 SPN 3951 — Body/Chassis parameter

What it means

Power Take-off (PTO) Driven Equipment Feedback Switch. This fault occurs when the ECM detects an irrational signal or a circuit failure related to the PTO engagement feedback loop.