What causes a SPN 3078 code?

SPN 3078 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 3078 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3078 active.

How do I fix SPN 3078?

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 3078

SPN 3078 Fuel Pressure Regulator/Pump Inlet Pressure Low

What it means

Indicates that the fuel pressure measured at the inlet of the high-pressure pump is lower than the commanded or expected value, typically suggesting a restriction in the low-pressure fuel side.