What causes a SPN 4900 code?

SPN 4900 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 4900 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4900 active.

How do I fix SPN 4900?

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 4900

Allison transmission code P4900

What it means

Internal Control Module Memory Check Sum Error. The TCM has detected a mismatch in its internal memory checksum, indicating a processor or memory corruption issue.