What causes a SPN 520280 code?

SPN 520280 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 520280 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 520280 active.

How do I fix SPN 520280?

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 520280

EDU Pressure Sensor Signal Failed Low

What it means

Diesel Exhaust Fluid (DEF) Pump Pressure Sensor Signal Failed Low indicates the sensor voltage is below the minimum calibrated threshold (typically < 0.25V).