What causes a SPN 4709 code?

SPN 4709 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 4709 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4709 active.

How do I fix SPN 4709?

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 4709

Allison transmission code P4709

What it means

Transmission Main Pressure - Voltage Below Normal, or Rate of Change Monitoring. This relates to the TCM detecting an unexpected signal from the main pressure sensor.