What causes a U3111 code?

U3111 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 U3111 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with U3111 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

U3111

Manufacturer-specific network code U3111

What it means

Communication failure in the vehicle's internal data network involving specific auxiliary control modules. This code indicates a loss of data integrity or heartbeat from a manufacturer-defined subsystem.