What causes a SPN 4106 code?

SPN 4106 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 4106 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 4106 active.

How do I fix SPN 4106?

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 4106

Allison transmission code P4106

What it means

IMS (Internal Mode Switch) Circuit - Short to Ground. This indicates the TCM has detected an unexpected ground signal on one of the switch signal lines (A, B, C, or P).