What causes a SPN 4807 code?

SPN 4807 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 4807 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4807 active.

How do I fix SPN 4807?

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 4807

Allison transmission code P4807

What it means

Retarder Pressure Control Solenoid Signal Circuit Low Input. This indicates the TCM has detected a voltage below the calibrated threshold on the retarder solenoid circuit.