What causes a P1040 code?

P1040 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 P1040 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P1040 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

P1040

DOCP Doc pressure too low fault

What it means

Diesel Oxidation Catalyst fuel Pressure (DOCP) is lower than the commanded setpoint during an active regeneration event.

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

Log in Sign up free