What causes a SPN 7791 code?

SPN 7791 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 SPN 7791 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 7791 active.

How do I fix SPN 7791?

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

J1939 SPN

SPN 7791

Cummins fault code 7791

What it means

Fuel Pressure Sensor Circuit - Voltage Below Normal OR Shorted to Low Source. This code indicates the ECM detects a signal voltage from the fuel pressure sensor that is lower than the calibrated threshold.