What causes a SPN 944 code?

SPN 944 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 944 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 944 active.

How do I fix SPN 944?

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 944

J1939 SPN 944 — Engine Management parameter

What it means

SPN 944 typically refers to the Heated Seat or Heated Mirror output status/control within the chassis or cabin management system (though categorized under Engine Management in some J1939 subsets). It indicates a fault in the circuit managing auxiliary heating elements.