What causes a SPN 950 code?

SPN 950 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 950 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 950 active.

How do I fix SPN 950?

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 950

J1939 SPN 950 — Engine Management parameter

What it means

SPN 950 specifically refers to the Engine Protection Override Switch. This input allows the operator to temporarily bypass engine derates or shutdowns during critical safety situations.