What causes a SPN 4346 code?

SPN 4346 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 4346 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4346 active.

How do I fix SPN 4346?

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 4346

Detroit DD13/DD15/DD16 SPN 4346

What it means

Selective Catalytic Reduction (SCR) Inlet Heater Circuit - Voltage Below Normal or Shorted to Low Source. This fault indicates the ACM detects an open circuit or short in the SCR line heater.