What causes a SPN 4501 code?

SPN 4501 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 4501 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4501 active.

How do I fix SPN 4501?

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 4501

Allison transmission code P4501

What it means

Internal Control Module Memory Checksum Error. This indicates that the Allison TCM has detected an internal calculation error or data corruption within its own memory.