What causes a SPN 973 code?

SPN 973 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 973 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 973 active.

How do I fix SPN 973?

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 973

SPN 973 - Fan Drive Control Module Circuit High or Shorted

What it means

Indicates an electrical fault in the engine cooling fan clutch control circuit, typically where the ECM detects a short to voltage or an open circuit in the fan solenoid wiring.