What causes a SPN 4405 code?

SPN 4405 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 4405 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4405 active.

How do I fix SPN 4405?

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 4405

Allison transmission code P4405

What it means

Shift Pressure Deviation High. This code indicates that the transmission control module (TCM) detected a pressure mismatch during a shift, suggesting the pressure did not drop or rise as expected within the calibrated time.