What causes a SPN 4308 code?

SPN 4308 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 4308 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4308 active.

How do I fix SPN 4308?

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 4308

Allison transmission code P4308

What it means

Pressure Control Solenoid (PCS) 2 Control Circuit Low - The TCM has detected an abnormally low voltage or an open circuit in the circuit for pressure control solenoid 2.