What causes a P0401 code?

P0401 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 P0401 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P0401 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

Log in Sign up

OBD-II

P0401

Exhaust Gas Recirculation Flow Insufficient

What it means

EGR flow too low

Sign in to view symptoms, probable causes, diagnostic steps, severity, and related codes

Log in Sign up free