What causes a SPN 1234 code?

SPN 1234 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 1234 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 1234 active.

How do I fix SPN 1234?

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

Log in Sign up

J1939 SPN

SPN 1234

Wait to Start Lamp

What it means

Circuit failure for the intake heater or glow plug indicator lamp. Common in cold-start systems.

Sign in to view symptoms, probable causes, diagnostic steps, severity, and related codes

Log in Sign up free