What causes a U0406 code?

U0406 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 U0406 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with U0406 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

U0406

Network/CAN bus communication code U0406

What it means

Invalid Data Received from Fuel Injector Control Module. The PCM is receiving timing or firing data from the FICM that does not meet safety standards.