What causes a SPN 4291 code?

SPN 4291 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 4291 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4291 active.

How do I fix SPN 4291?

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 4291

Cummins fault code 4291

What it means

Wait-to-Start Lamp - Voltage Below Normal or Shorted to Low Source. The ECM has detected a low voltage or open circuit on the Wait-to-Start (pre-heat) indicator lamp circuit.