What causes a U0838 code?

U0838 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 U0838 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with U0838 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

U0838

Network/CAN bus communication code U0838

What it means

Lost communication with the Exhaust Gas Recirculation (EGR) Control Module. The ECU has lost its digital link to the controller managing EGR valve position.