What causes a SPN 3506 code?

SPN 3506 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 3506 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3506 active.

How do I fix SPN 3506?

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 3506

J1939 SPN 3506 — Body/Chassis parameter

What it means

Aftertreatment 1 SCR Catalyst System Monitor. Note: In many J1939 contexts, 3506 specifically refers to secondary signal plausibility or body-specific chassis monitoring parameters often related to signal aliasing or configuration mismatches.