What causes a SPN 1990 code?

SPN 1990 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 1990 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 1990 active.

How do I fix SPN 1990?

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.

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J1939 SPN

SPN 1990

DPF Active Regeneration Inhibited Due to System Timeout

What it means

The diesel particulate filter regeneration cycle was stopped because the process took too long to complete.

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