What causes a P109D code?

P109D 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 P109D code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with P109D 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

P109D

High Pressure (dump) Valve current feedback max range fault

What it means

High Pressure (dump) Valve current feedback max range fault. This indicates the ECM detected a current return from the fuel pressure relief valve that exceeds the calibrated maximum limit.