What causes a SPN 6321 code?

SPN 6321 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 6321 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 6321 active.

How do I fix SPN 6321?

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 6321

Cummins fault code 6321

What it means

Electronic Front Radar Sensor - Signal Incorrect. This code relates to the Collision Mitigation System (CMS) or Adaptive Cruise Control (ACC) not receiving reliable data from the radar.