What causes a SPN 520 code?

SPN 520 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 520 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 520 active.

How do I fix SPN 520?

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 520

SPN 520 — Cruise Control Set Speed

What it means

Indicates an issue with the cruise control set speed parameter or the vehicle's ability to maintain/calculate the requested speed.