What causes a SPN 3787 code?

SPN 3787 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 3787 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3787 active.

How do I fix SPN 3787?

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 3787

J1939 SPN 3787 — Body/Chassis parameter

What it means

SPN 3787 is typically associated with Aftertreatment DPF Active Regeneration Inhibit Due to Low Temperature. It indicates that the system is unable to achieve or maintain the heat required to perform a parked or active regeneration.