What causes a SPN 44 code?

SPN 44 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 44 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 44 active.

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 44

J1939 SPN 44 — Engine parameter

What it means

SPN 44 typically indicates a fault with the Ambient Air Temperature sensor signal. The ECM uses this data to adjust fueling, timing, and fan engagement.