What causes a SPN 4504 code?

SPN 4504 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 4504 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4504 active.

How do I fix SPN 4504?

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 4504

Allison transmission code P4504

What it means

SPN 4504 corresponds to Allison P2733 or similar solenoid performance/electrical issues, specifically indicating a solenoid that is stuck off or experiencing an electrical circuit malfunction affecting shift or pressure control.