What causes a SPN 5551 code?

SPN 5551 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 5551 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 5551 active.

How do I fix SPN 5551?

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 5551

Cummins fault code 5551

What it means

Aftertreatment 1 SCR Temperature 1 Sensor Circuit - Voltage Below Normal or Shorted to Low Source. This identifies an electrical issue with the SCR inlet temperature sensor.