What causes a SPN 4806 code?

SPN 4806 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 4806 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4806 active.

How do I fix SPN 4806?

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 4806

Allison transmission code P4806

What it means

Secondary CPU Internal Monitoring Error - The Transmission Control Module (TCM) has detected an internal logic error or memory corruption between the primary and monitoring processors.