What causes a SPN 845 code?

SPN 845 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 845 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 845 active.

How do I fix SPN 845?

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 845

J1939 SPN 845 — Engine Management parameter

What it means

SPN 845 indicates a fault with the Crankshaft Position (CKP) sensor signal. This usually refers to an irrational signal, loss of synchronization, or erratic pulse timing relative to the camshaft position.