What causes a U3301 code?

U3301 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 U3301 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with U3301 active.

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

OBD-II

U3301

Manufacturer-specific network code U3301

What it means

U3301 is a network communication code indicating a loss of communication or data synchronization between the Transmission Control Module (TCM) and other primary controllers like the PCM or BCM.