What causes a SPN 673 code?

SPN 673 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 673 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 673 active.

How do I fix SPN 673?

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 673

J1939 SPN 673 — Engine Management parameter

What it means

Fault SPN 673 indicates an issue with the Engine Speed (Crankshaft Position) sensor signal, specifically regarding signal quality, frequency, or loss of synchronization with the camshaft.