What causes a SPN 109 code?

SPN 109 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 109 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 109 active.

How do I fix SPN 109?

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 109

Engine Coolant Pressure

What it means

Monitors the pressure of the coolant fluid within the engine cooling system to prevent cavitation or leaks.

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

Log in Sign up free