What causes a SPN 520249 code?

SPN 520249 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 520249 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 520249 active.

How do I fix SPN 520249?

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 520249

SCR Inlet Temperature High

What it means

The Aftertreatment Control Module (ACM) detects that the exhaust temperature entering the SCR catalyst has exceeded the maximum safe operating threshold (typically above 700°C / 1292°F).