What causes a SPN 4773 code?

SPN 4773 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 4773 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4773 active.

How do I fix SPN 4773?

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 4773

Detroit DD13/DD15/DD16 SPN 4773

What it means

Aftertreatment 1 Intake Temperature - Data Erratic, Intermittent, or Incorrect. The ACM detects that the ATD Inlet Temperature sensor is fluctuating outside of normal parameters compared to other exhaust sensors.