What causes a SPN 3705 code?

SPN 3705 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 3705 code?

Drivability depends on the severity. Check the severity rating and verified driver reports on this page before continuing to drive with SPN 3705 active.

How do I fix SPN 3705?

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 3705

J1939 SPN 3705 — Body/Chassis parameter

What it means

DPF Regeneration Inhibit Switch Switch State. This code typically indicates the ECM is receiving an invalid or irrational signal from the dash-mounted DPF inhibit switch via the J1939 data link.