What causes a SPN 4704 code?

SPN 4704 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 4704 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4704 active.

How do I fix SPN 4704?

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 4704

Allison transmission code P4704

What it means

Allison Transmission Internal Mode Switch (IMS) Parity Performance. The TCM has detected an invalid combination of signals from the IMS, meaning it cannot verify the physical position of the gear selector lever.