What causes a SPN 4277 code?

SPN 4277 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 4277 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4277 active.

How do I fix SPN 4277?

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 4277

Cummins fault code 4277

What it means

Aftertreatment 1 Diesel Exhaust Fluid Line Heater 5 - Voltage Below Normal or Shorted to Low Source. This code specifically points to an electrical issue with the 'Suction Line' heater.