What causes a SPN 6993 code?

SPN 6993 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 6993 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 6993 active.

How do I fix SPN 6993?

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 6993

Cummins fault code 6993

What it means

Intake Manifold Air Heater 1 Circuit - Voltage Below Normal or Shorted to Low Source. The ECM detects that the commanded state of the heater does not match the actual feedback voltage.